101
|
Yuan W, Tutuncuoglu G, Mohabir A, Liu L, Feldman LC, Filler MA, Shan JW. Contactless Electrical and Structural Characterization of Semiconductor Nanowires with Axially Modulated Doping Profiles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1805140. [PMID: 30884159 DOI: 10.1002/smll.201805140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 02/14/2019] [Indexed: 06/09/2023]
Abstract
Efficient characterization of semiconductor nanowires having complex dopant profiles or heterostructures is critical to fully understand these materials and the devices built from them. Existing electrical characterization techniques are slow and laborious, particularly for multisegment nanowires, and impede the statistical understanding of highly variable samples. Here, it is shown that electro-orientation spectroscopy (EOS)-a high-throughput, noncontact method for statistically characterizing the electrical properties of entire nanowire ensembles-can determine the conductivity and dimensions of two distinct segments in individual Si nanowires with axially encoded dopant profiles. This analysis combines experimental measurements and computational simulations to determine the electrical conductivity of the nominally undoped segment of two-segment Si nanowires, as well as the ratio of the segment lengths. The efficacy of this approach is demonstrated by comparing results generated by EOS with conventional four-point-probe measurements. This work provides new insights into the control and variability of semiconductor nanowires for electronic applications and is a critical first step toward the high-throughput interrogation of complete nanowire-based devices.
Collapse
Affiliation(s)
- Wuhan Yuan
- Department of Mechanical & Aerospace Engineering, Rutgers University, Piscataway, NJ, 08854, USA
| | - Gozde Tutuncuoglu
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Amar Mohabir
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Liping Liu
- Department of Mathematics and Department of Mechanical & Aerospace Engineering, Rutgers University, Piscataway, NJ, 08854, USA
| | - Leonard C Feldman
- Department of Material Science & Engineering and Department of Physics & Astronomy, Rutgers University, Piscataway, NJ, 08854, USA
| | - Michael A Filler
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Jerry W Shan
- Department of Mechanical & Aerospace Engineering, Rutgers University, Piscataway, NJ, 08854, USA
| |
Collapse
|
102
|
Gazibegovic S, Badawy G, Buckers TLJ, Leubner P, Shen J, de Vries FK, Koelling S, Kouwenhoven LP, Verheijen MA, Bakkers EPAM. Bottom-Up Grown 2D InSb Nanostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1808181. [PMID: 30779385 DOI: 10.1002/adma.201808181] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/31/2019] [Indexed: 06/09/2023]
Abstract
Low-dimensional high-quality InSb materials are promising candidates for next-generation quantum devices due to the high carrier mobility, low effective mass, and large g-factor of the heavy element compound InSb. Various quantum phenomena are demonstrated in InSb 2D electron gases and nanowires. A combination of the best features of these two systems (pristine nanoscale and flexible design) is desirable to realize, e.g., the multiterminal topological Josephson device. Here, controlled growth of 2D nanostructures, nanoflakes, on an InSb platform is demonstrated. An assembly of nanoflakes with various dimensions and morphologies, thinner than the Bohr radius of InSb, are fabricated. Importantly, the growth of either nanowires or nanoflakes can be enforced experimentally by setting growth and substrate design parameters properly. Hall bar measurements on the nanostructures yield mobilities up to ≈20 000 cm2 V-1 s-1 and detect quantum Hall plateaus. This allows to see the system as a viable nanoscale 2D platform for future quantum devices.
Collapse
Affiliation(s)
- Sasa Gazibegovic
- Department of Applied Physics, Eindhoven University of Technology, 5600, MB, Eindhoven, The Netherlands
- QuTech and Kavli Institute of NanoScience, Delft University of Technology, 2600, GA, Delft, The Netherlands
| | - Ghada Badawy
- Department of Applied Physics, Eindhoven University of Technology, 5600, MB, Eindhoven, The Netherlands
| | - Thijs L J Buckers
- Department of Applied Physics, Eindhoven University of Technology, 5600, MB, Eindhoven, The Netherlands
| | - Philipp Leubner
- Department of Applied Physics, Eindhoven University of Technology, 5600, MB, Eindhoven, The Netherlands
- QuTech and Kavli Institute of NanoScience, Delft University of Technology, 2600, GA, Delft, The Netherlands
| | - Jie Shen
- QuTech and Kavli Institute of NanoScience, Delft University of Technology, 2600, GA, Delft, The Netherlands
| | - Folkert K de Vries
- QuTech and Kavli Institute of NanoScience, Delft University of Technology, 2600, GA, Delft, The Netherlands
| | - Sebastian Koelling
- Department of Applied Physics, Eindhoven University of Technology, 5600, MB, Eindhoven, The Netherlands
| | - Leo P Kouwenhoven
- QuTech and Kavli Institute of NanoScience, Delft University of Technology, 2600, GA, Delft, The Netherlands
- Microsoft Quantum Lab Delft, Delft University of Technology, 2600, GA, Delft, The Netherlands
| | - Marcel A Verheijen
- Department of Applied Physics, Eindhoven University of Technology, 5600, MB, Eindhoven, The Netherlands
- Eurofins Material Science Netherlands B.V., High Tech Campus, 5656, AE, Eindhoven, The Netherlands
| | - Erik P A M Bakkers
- Department of Applied Physics, Eindhoven University of Technology, 5600, MB, Eindhoven, The Netherlands
- QuTech and Kavli Institute of NanoScience, Delft University of Technology, 2600, GA, Delft, The Netherlands
| |
Collapse
|
103
|
He Z, Maurice JL, Li Q, Pribat D. Direct evidence of 2H hexagonal Si in Si nanowires. NANOSCALE 2019; 11:4846-4853. [PMID: 30816896 DOI: 10.1039/c8nr10370d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Hexagonal Si (2H polytype) has attracted great interest because of its unique physical properties and wide range of potential applications. For example, it might be used in heterojunctions based on hexagonal and cubic Si. Although hexagonal Si has been reported in Si nanowires, its existence is doubted because structural defects of diamond cubic Si can produce structural signals similar to those attributed to hexagonal Si. Here, through the use of atomic resolution high-angle annular dark-field scanning transmission electron microscopy imaging, we unambiguously report the coherent intergrowth of diamond cubic (3C polytype) and 2H hexagonal Si in Si nanowires grown by chemical vapor deposition. A model describing the intergrowth of 3C and 2H Si is proposed and the reasons for the generation of 2H Si are discussed in detail.
Collapse
Affiliation(s)
- Zhanbing He
- State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China.
| | | | | | | |
Collapse
|
104
|
Fundamental aspects to localize self-catalyzed III-V nanowires on silicon. Nat Commun 2019; 10:869. [PMID: 30787305 PMCID: PMC6382777 DOI: 10.1038/s41467-019-08807-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 01/25/2019] [Indexed: 11/19/2022] Open
Abstract
III-V semiconductor nanowires deterministically placed on top of silicon electronic platform would open many avenues in silicon-based photonics, quantum technologies and energy harvesting. For this to become a reality, gold-free site-selected growth is necessary. Here, we propose a mechanism which gives a clear route for maximizing the nanowire yield in the self-catalyzed growth fashion. It is widely accepted that growth of nanowires occurs on a layer-by-layer basis, starting at the triple-phase line. Contrary to common understanding, we find that vertical growth of nanowires starts at the oxide-substrate line interface, forming a ring-like structure several layers thick. This is granted by optimizing the diameter/height aspect ratio and cylindrical symmetry of holes, which impacts the diffusion flux of the group V element through the well-positioned group III droplet. This work provides clear grounds for realistic integration of III-Vs on silicon and for the organized growth of nanowires in other material systems. The ability to place perfectly aligned vertical nanowires at chosen positions on a silicon substrate is an important challenge in device fabrication. Here, the authors propose a mechanism to explain self-catalyzed III-V nanowire growth on silicon, providing valuable insights for growing high yield nanowire arrays.
Collapse
|
105
|
Mårtensson EK, Lehmann S, Dick KA, Johansson J. Simulation of GaAs Nanowire Growth and Crystal Structure. NANO LETTERS 2019; 19:1197-1203. [PMID: 30618259 DOI: 10.1021/acs.nanolett.8b04637] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Growing GaAs nanowires with well-defined crystal structures is a challenging task, but may be required for the fabrication of future devices. In terms of crystal phase selection, the connection between theory and experiment is limited, leaving experimentalists with a trial and error approach to achieve the desired crystal structures. In this work, we present a modeling approach designed to provide the missing connection, combining classical nucleation theory, stochastic simulation, and mass transport through the seed particle. The main input parameters for the model are the flows of the growth species and the temperature of the process, giving the simulations the same flexibility as experimental growth. The output of the model can also be directly compared to experimental observables, such as crystal structure of each bilayer throughout the length of the nanowire and the composition of the seed particle. The model thus enables for observed experimental trends to be directly explored theoretically. Here, we use the model to simulate nanowire growth with varying As flows, and our results match experimental trends with a good agreement. By analyzing the data from our simulation, we find theoretical explanations for these experimental results, providing new insights into how the crystal structure is affected by the experimental parameters available for growth.
Collapse
Affiliation(s)
- Erik K Mårtensson
- Solid State Physics and NanoLund , Lund University , P.O. Box 118, Lund 22100 , Sweden
| | - Sebastian Lehmann
- Solid State Physics and NanoLund , Lund University , P.O. Box 118, Lund 22100 , Sweden
| | - Kimberly A Dick
- Solid State Physics and NanoLund , Lund University , P.O. Box 118, Lund 22100 , Sweden
- Centre for Analysis and Synthesis , Lund University , P.O. Box 124, Lund 22100 , Sweden
| | - Jonas Johansson
- Solid State Physics and NanoLund , Lund University , P.O. Box 118, Lund 22100 , Sweden
| |
Collapse
|
106
|
Amato M, Ossicini S, Canadell E, Rurali R. Preferential Positioning, Stability, and Segregation of Dopants in Hexagonal Si Nanowires. NANO LETTERS 2019; 19:866-876. [PMID: 30608707 DOI: 10.1021/acs.nanolett.8b04083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We studied the physics of common p- and n-type dopants in hexagonal-diamond Si, a Si polymorph that can be synthesized in nanowire geometry without the need of extreme pressure conditions, by means of first-principles electronic structure calculations and compared our results with those for the well-known case of cubic-diamond nanowires. We showed that (i) as observed in recent experiments, at larger diameters (beyond the quantum confinement regime) p-type dopants prefer the hexagonal-diamond phase with respect to the cubic one as a consequence of the stronger degree of three-fold coordination of the former, while n-type dopants are at a first approximation indifferent to the polytype of the host lattice; (ii) in ultrathin nanowires, because of the lower symmetry with respect to bulk systems and the greater freedom of structural relaxation, the order is reversed and both types of dopant slightly favor substitution at cubic lattice sites; (iii) the difference in formation energies leads, particularly in thicker nanowires, to larger concentration differences in different polytypes, which can be relevant for cubic-hexagonal homojunctions; (iv) ultrasmall diameters exhibit, regardless of the crystal phase, a pronounced surface segregation tendency for p-type dopants. Overall these findings shed light on the role of crystal phase in the doping mechanism at the nanoscale and could have a great potential in view of the recent experimental works on group IV nanowires polytypes.
Collapse
Affiliation(s)
- Michele Amato
- Laboratoire de Physique des Solides (LPS) , CNRS, Université Paris-Sud, Université Paris-Saclay, Centre Scientifique d'Orsay , F91405 Orsay cedex , France
| | - Stefano Ossicini
- "Centro S3", CNR-Istituto di Nanoscienze , Via Campi 213/A , 41125 Modena , Italy
- Dipartimento di Scienze e Metodi dell'Ingegneria, Centro Interdipartimentale En&Tech , Universitá di Modena e Reggio Emilia , Via Amendola 2 Pad. Morselli , I-42100 Reggio Emilia , Italy
| | - Enric Canadell
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra , 08193 Bellaterra, Barcelona , Spain
| | - Riccardo Rurali
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra , 08193 Bellaterra, Barcelona , Spain
| |
Collapse
|
107
|
Koivusalo ES, Hakkarainen TV, Galeti HVA, Gobato YG, Dubrovskii VG, Guina MD. Deterministic Switching of the Growth Direction of Self-Catalyzed GaAs Nanowires. NANO LETTERS 2019; 19:82-89. [PMID: 30537843 DOI: 10.1021/acs.nanolett.8b03365] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The typical vapor-liquid-solid growth of nanowires is restricted to a vertical one-dimensional geometry, while there is a broad interest for more complex structures in the context of electronics and photonics applications. Controllable switching of the nanowire growth direction opens up new horizons in the bottom-up engineering of self-assembled nanostructures, for example, to fabricate interconnected nanowires used for quantum transport measurements. In this work, we demonstrate a robust and highly controllable method for deterministic switching of the growth direction of self-catalyzed GaAs nanowires. The method is based on the modification of the droplet-nanowire interface in the annealing stage without any fluxes and subsequent growth in the horizontal direction by a twin-mediated mechanism with indications of a novel type of interface oscillations. A 100% yield of switching the nanowire growth direction from vertical to horizontal is achieved by systematically optimizing the growth parameters. A kinetic model describing the competition of different interface structures is introduced to explain the switching mechanism and the related nanowire geometries. The model also predicts that the growth of similar structures is possible for all vapor-liquid-solid nanowires with commonly observed truncated facets at the growth interface.
Collapse
Affiliation(s)
- Eero S Koivusalo
- Optoelectronics Research Centre , Tampere University of Technology , P.O. Box 692, Tampere 33101 , Finland
| | - Teemu V Hakkarainen
- Optoelectronics Research Centre , Tampere University of Technology , P.O. Box 692, Tampere 33101 , Finland
| | - Helder V A Galeti
- Electrical Engineering Department , Federal University of São Carlos , São Carlos , São Paulo 13565-905 , Brazil
| | - Yara G Gobato
- Physics Department , Federal University of São Carlos , São Carlos , São Paulo 13565-905 , Brazil
| | | | - Mircea D Guina
- Optoelectronics Research Centre , Tampere University of Technology , P.O. Box 692, Tampere 33101 , Finland
| |
Collapse
|
108
|
Aseev P, Fursina A, Boekhout F, Krizek F, Sestoft JE, Borsoi F, Heedt S, Wang G, Binci L, Martí-Sánchez S, Swoboda T, Koops R, Uccelli E, Arbiol J, Krogstrup P, Kouwenhoven LP, Caroff P. Selectivity Map for Molecular Beam Epitaxy of Advanced III-V Quantum Nanowire Networks. NANO LETTERS 2019; 19:218-227. [PMID: 30521341 PMCID: PMC6331184 DOI: 10.1021/acs.nanolett.8b03733] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/15/2018] [Indexed: 05/19/2023]
Abstract
Selective-area growth is a promising technique for enabling of the fabrication of the scalable III-V nanowire networks required to test proposals for Majorana-based quantum computing devices. However, the contours of the growth parameter window resulting in selective growth remain undefined. Herein, we present a set of experimental techniques that unambiguously establish the parameter space window resulting in selective III-V nanowire networks growth by molecular beam epitaxy. Selectivity maps are constructed for both GaAs and InAs compounds based on in situ characterization of growth kinetics on GaAs(001) substrates, where the difference in group III adatom desorption rates between the III-V surface and the amorphous mask area is identified as the primary mechanism governing selectivity. The broad applicability of this method is demonstrated by the successful realization of high-quality InAs and GaAs nanowire networks on GaAs, InP, and InAs substrates of both (001) and (111)B orientations as well as homoepitaxial InSb nanowire networks. Finally, phase coherence in Aharonov-Bohm ring experiments validates the potential of these crystals for nanoelectronics and quantum transport applications. This work should enable faster and better nanoscale crystal engineering over a range of compound semiconductors for improved device performance.
Collapse
Affiliation(s)
- Pavel Aseev
- QuTech
and Kavli Institute of NanoScience, Delft
University of Technology, Lorentzweg 1, 2600 GA Delft, The Netherlands
- E-mail:
| | - Alexandra Fursina
- Microsoft
Station Q at Delft University of Technology, 2600 GA Delft, Netherlands
| | - Frenk Boekhout
- QuTech
and Netherlands Organization for Applied Scientific Research (TNO), Stieltjesweg 1, 2628 CK Delft, The Netherlands
| | - Filip Krizek
- Center
For Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Joachim E. Sestoft
- Center
For Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Francesco Borsoi
- QuTech
and Kavli Institute of NanoScience, Delft
University of Technology, Lorentzweg 1, 2600 GA Delft, The Netherlands
| | - Sebastian Heedt
- QuTech
and Kavli Institute of NanoScience, Delft
University of Technology, Lorentzweg 1, 2600 GA Delft, The Netherlands
| | - Guanzhong Wang
- QuTech
and Kavli Institute of NanoScience, Delft
University of Technology, Lorentzweg 1, 2600 GA Delft, The Netherlands
| | - Luca Binci
- QuTech
and Kavli Institute of NanoScience, Delft
University of Technology, Lorentzweg 1, 2600 GA Delft, The Netherlands
| | - Sara Martí-Sánchez
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Bellaterra, Barcelona, Catalonia, Spain
| | - Timm Swoboda
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Bellaterra, Barcelona, Catalonia, Spain
| | - René Koops
- QuTech
and Netherlands Organization for Applied Scientific Research (TNO), Stieltjesweg 1, 2628 CK Delft, The Netherlands
| | - Emanuele Uccelli
- QuTech
and Netherlands Organization for Applied Scientific Research (TNO), Stieltjesweg 1, 2628 CK Delft, The Netherlands
| | - Jordi Arbiol
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Bellaterra, Barcelona, Catalonia, Spain
- ICREA, Passeig de Lluís Companys
23, 08010 Barcelona, Catalonia, Spain
| | - Peter Krogstrup
- Center
For Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Leo P. Kouwenhoven
- QuTech
and Kavli Institute of NanoScience, Delft
University of Technology, Lorentzweg 1, 2600 GA Delft, The Netherlands
- Microsoft
Station Q at Delft University of Technology, 2600 GA Delft, Netherlands
- E-mail:
| | - Philippe Caroff
- Microsoft
Station Q at Delft University of Technology, 2600 GA Delft, Netherlands
- E-mail:
| |
Collapse
|
109
|
Berdnikov Y, Sibirev NV, Khayrudinov V, Alaferdov A, Moshkalev S, Ubyivovk EV, Lipsanen H, Bouravleuv A. Growth of GaAs nanowire–graphite nanoplatelet hybrid structures. CrystEngComm 2019. [DOI: 10.1039/c9ce01027k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The scenarios of MOVPE growth of planar and non-planar GaAs nanowires are controlled with graphite nanoplatelet substrates and catalyst placement.
Collapse
Affiliation(s)
| | | | | | - Andrei Alaferdov
- Center for Semiconductor Components
- State University of Campinas
- Campinas
- Brazil
| | - Stanislav Moshkalev
- Center for Semiconductor Components
- State University of Campinas
- Campinas
- Brazil
| | | | - Harri Lipsanen
- Department of Electronics and Nanoengineering
- Micronova, Aalto University
- Finland
| | - Alexei Bouravleuv
- Department of Electronics and Nanoengineering
- Micronova, Aalto University
- Finland
- St. Petersburg Academic University
- 194021 St. Petersburg
| |
Collapse
|
110
|
Gao H, Lysevych M, Tan HH, Jagadish C, Zou J. The effect of Sn addition on GaAs nanowire grown by vapor-liquid-solid growth mechanism. NANOTECHNOLOGY 2018; 29:465601. [PMID: 30179858 DOI: 10.1088/1361-6528/aadedd] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Impurity addition is a crucial aspect for III-V nanowire growth. In this study, we demonstrated the effect of the Sn addition on GaAs nanowire growth by metal-organic chemical vapor deposition. With increasing the tetraethyltin flow rate, the nanowire axial growth was suppressed while the nanowire lateral growth was promoted, as well as planar defects were increased. Systematic electron microscopy characterizations suggested that the Sn addition tuned the catalyst composition, changed the vapor-solid-liquid surfaces energies and hindered the Ga atoms diffusion on nanowire sidewalls, which is responsible for the observed changes in morphology and structural quality of grown GaAs nanowires. This study contributes to understanding the role of impurity dopants on III-V nanowires growth, which will be of benefit for the design and fabrication of future nanowire-based devices.
Collapse
Affiliation(s)
- Han Gao
- Materials Engineering, The University of Queensland, St Lucia, Queensland 4072, Australia
| | | | | | | | | |
Collapse
|
111
|
Piazza V, Vettori M, Ahmed AA, Lavenus P, Bayle F, Chauvin N, Julien FH, Regreny P, Patriarche G, Fave A, Gendry M, Tchernycheva M. Nanoscale investigation of a radial p-n junction in self-catalyzed GaAs nanowires grown on Si (111). NANOSCALE 2018; 10:20207-20217. [PMID: 30357204 DOI: 10.1039/c8nr03827a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
One obstacle for the development of nanowire (NW) solar cells is the challenge to assess and control their nanoscale electrical properties. In this work a top-cell made of p-n GaAs core/shell NWs grown on a Si(111) substrate by Molecular Beam Epitaxy (MBE) is investigated by high resolution charge collection microscopy. Electron Beam Induced Current (EBIC) analyses of single NWs have validated the formation of a homogeneous radial p-n junction over the entire length of the NWs. The radial geometry leads to an increase of the junction area by 38 times with respect to the NW footprint. The interface between the NWs and the Si(111) substrate does not show any electrical loss, which would have led to a decrease of the EBIC signal. Single NW I-V characteristics present a diodic behavior. A model of the radial junction single NW is proposed and the electrical parameters are estimated by numerical fitting of the I-Vs and of the EBIC map. Solar cells based on NW arrays were fabricated and analyzed by EBIC microscopy, which evidenced the presence of a Schottky barrier at the NW/ITO top contact. Improvement of the top contact quality is achieved by thermal annealing at 400 °C, which strongly reduces the parasitic Schottky barrier.
Collapse
Affiliation(s)
- Valerio Piazza
- Centre de Nanosciences et de Nanotechnologies (C2N), UMR 9001 CNRS, Univ. Paris Sud, Univ. Paris-Saclay, 8 Avenue de la Vauve, 91120 Palaiseau, France.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
112
|
Harmand JC, Patriarche G, Glas F, Panciera F, Florea I, Maurice JL, Travers L, Ollivier Y. Atomic Step Flow on a Nanofacet. PHYSICAL REVIEW LETTERS 2018; 121:166101. [PMID: 30387660 DOI: 10.1103/physrevlett.121.166101] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 07/14/2018] [Indexed: 05/25/2023]
Abstract
Crystal growth often proceeds by atomic step flow. When the surface area available for growth is limited, the nucleation and progression of the steps can be affected. This issue is particularly relevant to the formation of nanocrystals. We examine the case of Au-catalyzed GaAs nanowires, which we grow in a transmission electron microscope. Our in situ observations show that atomic layers nucleate at the periphery of the interface between the nanowire and the catalyst droplet. From this starting location, the atomic step flows within a restricted area of hexagonal shape. At specific partial coverages, the monolayer configuration changes abruptly. A simple model based on the geometry of the system and its edge energies explains these observations. In particular, we observe an inversion of the step curvature which reveals that the effective energy per unit length of monolayer edge is much lower at the interface periphery than inside the catalyst droplet.
Collapse
Affiliation(s)
- Jean-Christophe Harmand
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Sud, Université Paris-Saclay, Avenue de la Vauve, 91120 Palaiseau, France
| | - Gilles Patriarche
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Sud, Université Paris-Saclay, Avenue de la Vauve, 91120 Palaiseau, France
| | - Frank Glas
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Sud, Université Paris-Saclay, Avenue de la Vauve, 91120 Palaiseau, France
| | - Federico Panciera
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Sud, Université Paris-Saclay, Avenue de la Vauve, 91120 Palaiseau, France
| | - Ileana Florea
- Laboratoire de Physique des Interfaces et des Couches Minces, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
| | - Jean-Luc Maurice
- Laboratoire de Physique des Interfaces et des Couches Minces, Ecole polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
| | - Laurent Travers
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Sud, Université Paris-Saclay, Avenue de la Vauve, 91120 Palaiseau, France
| | - Yannick Ollivier
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Sud, Université Paris-Saclay, Avenue de la Vauve, 91120 Palaiseau, France
| |
Collapse
|
113
|
Zhang Z, Liu N, Li L, Su J, Chen PP, Lu W, Gao Y, Zou J. In Situ TEM Observation of Crystal Structure Transformation in InAs Nanowires on Atomic Scale. NANO LETTERS 2018; 18:6597-6603. [PMID: 30234307 DOI: 10.1021/acs.nanolett.8b03231] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In situ transmission electron microscopy investigation of structural transformation in III-V nanowires is essential for providing direct insight into the structural stability of III-V nanowires under elevated temperature. In this study, through in situ heating investigation in a transmission electron microscope, the detailed structural transformation of InAs nanowires from wurtzite structure to zinc-blende structure at the catalyst/nanowire interface is witnessed on the atomic level. Through detailed structural and dynamic analysis, it was found that the nucleation site of each new layer of InAs and catalyst surface energy play a decisive role in the growth of the zinc-blende structure. This study provides new insights into the growth mechanism of zinc-blende-structured III-V nanowires.
Collapse
Affiliation(s)
- Zhi Zhang
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO) , Huazhong University of Science and Technology (HUST) , Luoyu Road 1037 , Wuhan 430074 , P. R. China
| | - Nishuang Liu
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO) , Huazhong University of Science and Technology (HUST) , Luoyu Road 1037 , Wuhan 430074 , P. R. China
| | - Luying Li
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO) , Huazhong University of Science and Technology (HUST) , Luoyu Road 1037 , Wuhan 430074 , P. R. China
| | - Jun Su
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO) , Huazhong University of Science and Technology (HUST) , Luoyu Road 1037 , Wuhan 430074 , P. R. China
| | - Ping-Ping Chen
- National Laboratory for Infrared Physics , Shanghai Institute of Technical Physics, Chinese Academy of Sciences , 500 Yu-Tian Road , Shanghai 200083 , China
| | - Wei Lu
- National Laboratory for Infrared Physics , Shanghai Institute of Technical Physics, Chinese Academy of Sciences , 500 Yu-Tian Road , Shanghai 200083 , China
| | - Yihua Gao
- Center for Nanoscale Characterization & Devices (CNCD), School of Physics & Wuhan National Laboratory for Optoelectronics (WNLO) , Huazhong University of Science and Technology (HUST) , Luoyu Road 1037 , Wuhan 430074 , P. R. China
| | - Jin Zou
- Materials Engineering & Centre for Microscopy and Microanalysis , The University of Queensland , St. Lucia , Queensland 4072 , Australia
| |
Collapse
|
114
|
Zamani M, Tütüncüoglu G, Martí-Sánchez S, Francaviglia L, Güniat L, Ghisalberti L, Potts H, Friedl M, Markov E, Kim W, Leran JB, Dubrovskii VG, Arbiol J, Fontcuberta I Morral A. Optimizing the yield of A-polar GaAs nanowires to achieve defect-free zinc blende structure and enhanced optical functionality. NANOSCALE 2018; 10:17080-17091. [PMID: 30179246 DOI: 10.1039/c8nr05787g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Compound semiconductors exhibit an intrinsic polarity, as a consequence of the ionicity of their bonds. Nanowires grow mostly along the (111) direction for energetic reasons. Arsenide and phosphide nanowires grow along (111)B, implying a group V termination of the (111) bilayers. Polarity engineering provides an additional pathway to modulate the structural and optical properties of semiconductor nanowires. In this work, we demonstrate for the first time the growth of Ga-assisted GaAs nanowires with (111)A-polarity, with a yield of up to ∼50%. This goal is achieved by employing highly Ga-rich conditions which enable proper engineering of the energies of A and B-polar surfaces. We also show that A-polarity growth suppresses the stacking disorder along the growth axis. This results in improved optical properties, including the formation of AlGaAs quantum dots with two orders or magnitude higher brightness. Overall, this work provides new grounds for the engineering of nanowire growth directions, crystal quality and optical functionality.
Collapse
Affiliation(s)
- Mahdi Zamani
- Laboratoire des Matériaux Semiconducteurs, École Polytechnique Fédérale de Lausanne, EPFL, 1015 Lausanne, Switzerland.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
115
|
Jia S, Hu S, Zheng H, Wei Y, Meng S, Sheng H, Liu H, Zhou S, Zhao D, Wang J. Atomistic Interface Dynamics in Sn-Catalyzed Growth of Wurtzite and Zinc-Blende ZnO Nanowires. NANO LETTERS 2018; 18:4095-4099. [PMID: 29879357 DOI: 10.1021/acs.nanolett.8b00420] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Unraveling the phase selection mechanisms of semiconductor nanowires (NWs) is critical for the applications in future advanced nanodevices. In this study, the atomistic vapor-solid-liquid growth processes of Sn-catalyzed wurtzite (WZ) and zinc blende (ZB) ZnO are directly revealed based on the in situ transmission electron microscopy. The growth kinetics of WZ and ZB crystal phases in ZnO appear markedly different in terms of the NW-droplet interface, whereas the nucleation site as determined by the contact angle ϕ between the seed particle and the NW is found to be crucial for tuning the NW structure through combined experimental and theoretical investigations. These results offer an atomic-scale view into the dynamic growth process of ZnO NW, which has implications for the phase-controllable synthesis of II-VI compounds and heterostructures with tunable band structures.
Collapse
Affiliation(s)
- Shuangfeng Jia
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
| | - Shuaishuai Hu
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
| | - He Zheng
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
| | - Yanjie Wei
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
| | - Shuang Meng
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
| | - Huaping Sheng
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
| | - Huihui Liu
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
| | - Siyuan Zhou
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
| | - Dongshan Zhao
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
| | - Jianbo Wang
- School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China
- Science and Technology on High Strength Structural Materials Laboratory , Central South University , Changsha 410083 , China
| |
Collapse
|
116
|
Timofeeva M, Lang L, Timpu F, Renaut C, Bouravleuv A, Shtrom I, Cirlin G, Grange R. Anapoles in Free-Standing III-V Nanodisks Enhancing Second-Harmonic Generation. NANO LETTERS 2018; 18:3695-3702. [PMID: 29771127 DOI: 10.1021/acs.nanolett.8b00830] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Nonradiating electromagnetic configurations in nanostructures open new horizons for applications due to two essential features: a lack of energy losses and invisibility to the propagating electromagnetic field. Such radiationless configurations form a basis for new types of nanophotonic devices, in which a strong electromagnetic field confinement can be achieved together with lossless interactions between nearby components. In our work, we present a new design of free-standing disk nanoantennas with nonradiating current distributions for the optical near-infrared range. We show a novel approach to creating nanoantennas by slicing III-V nanowires into standing disks using focused ion-beam milling. We experimentally demonstrate the suppression of the far-field radiation and the associated strong enhancement of the second-harmonic generation from the disk nanoantennas. With a theoretical analysis of the electromagnetic field distribution using multipole expansions in both spherical and Cartesian coordinates, we confirm that the demonstrated nonradiating configurations are anapoles. We expect that the presented procedure of designing and producing disk nanoantennas from nanowires becomes one of the standard approaches to fabricating controlled chains of standing nanodisks with different designs and configurations. These chains can be essential building blocks for new types of lasers and sensors with low power consumption.
Collapse
Affiliation(s)
- Maria Timofeeva
- ETH Zurich , Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics , Auguste-Piccard Hof 1 , 8093 Zurich , Switzerland
| | - Lukas Lang
- ETH Zurich , Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics , Auguste-Piccard Hof 1 , 8093 Zurich , Switzerland
| | - Flavia Timpu
- ETH Zurich , Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics , Auguste-Piccard Hof 1 , 8093 Zurich , Switzerland
| | - Claude Renaut
- ETH Zurich , Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics , Auguste-Piccard Hof 1 , 8093 Zurich , Switzerland
| | - Alexei Bouravleuv
- Saint Petersburg Academic University , Ul. Khlopina 8/3 , 194021 Saint Petersburg , Russia
| | - Igor Shtrom
- Saint Petersburg Academic University , Ul. Khlopina 8/3 , 194021 Saint Petersburg , Russia
| | - George Cirlin
- ITMO University , Kronverkskiy 49 , 197101 Saint Petersburg , Russia
| | - Rachel Grange
- ETH Zurich , Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics , Auguste-Piccard Hof 1 , 8093 Zurich , Switzerland
| |
Collapse
|
117
|
Leshchenko ED, Kuyanov P, LaPierre RR, Dubrovskii VG. Tuning the morphology of self-assisted GaP nanowires. NANOTECHNOLOGY 2018; 29:225603. [PMID: 29509146 DOI: 10.1088/1361-6528/aab47b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Patterned arrays of self-assisted GaP nanowires (NWs) were grown on a Si substrate by gas source molecular beam epitaxy using various V/III flux ratios from 1-6, and various pitches from 360-1000 nm. As the V/III flux ratio was increased from 1-6, the NWs showed a change in morphology from outward tapering to straight, and eventually to inward tapering. The morphologies of the self-assisted GaP NWs are well described by a simple kinetic equation for the NW radius versus the position along the NW axis. The most important growth parameter that governs the NW morphology is the V/III flux ratio. Sharpened NWs with a stable radius equal to only 12 nm at a V/III flux of 6 were achieved, demonstrating their suitability for the insertion of quantum dots.
Collapse
Affiliation(s)
- E D Leshchenko
- ITMO University, Kronverkskiy pr. 49, 197101 St. Petersburg, Russia. Solid State Physics and NanoLund, Lund University, Box 118, SE-22100 Lund, Sweden
| | | | | | | |
Collapse
|
118
|
Sanchez AM, Gott JA, Fonseka HA, Zhang Y, Liu H, Beanland R. Stable Defects in Semiconductor Nanowires. NANO LETTERS 2018; 18:3081-3087. [PMID: 29624404 DOI: 10.1021/acs.nanolett.8b00620] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Semiconductor nanowires are commonly described as being defect-free due to their ability to expel mobile defects with long-range strain fields. Here, we describe previously undiscovered topologically protected line defects with null Burgers vector that, unlike dislocations, are stable in nanoscale crystals. We analyze the defects present in semiconductor nanowires in regions of imperfect crystal growth, i.e., at the nanowire tip formed during consumption of the droplet in self-catalyzed vapor-liquid-solid growth and subsequent vapor-solid shell growth. We use a form of the Burgers circuit method that can be applied to multiply twinned material without difficulty. Our observations show that the nanowire microstructure is very different from bulk material, with line defects either (a) trapped by locks or other defects, (b) arranged as dipoles or groups with a zero total Burgers vector, or (c) have a zero Burgers vector. We find two new line defects with a null Burgers vector, formed from the combination of partial dislocations in twinned material. The most common defect is the three-monolayer high twin facet with a zero Burgers vector. Studies of individual nanowires using cathodoluminescence show that optical emission is quenched in defective regions, showing that they act as strong nonradiative recombination centers.
Collapse
Affiliation(s)
- A M Sanchez
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - J A Gott
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - H A Fonseka
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Y Zhang
- Department of Electronic and Electrical Engineering , University College London , Torrington Place , London WC1E 7JE , United Kingdom
| | - H Liu
- Department of Electronic and Electrical Engineering , University College London , Torrington Place , London WC1E 7JE , United Kingdom
| | - R Beanland
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| |
Collapse
|
119
|
Oehler F, Cattoni A, Scaccabarozzi A, Patriarche G, Glas F, Harmand JC. Measuring and Modeling the Growth Dynamics of Self-Catalyzed GaP Nanowire Arrays. NANO LETTERS 2018; 18:701-708. [PMID: 29257888 DOI: 10.1021/acs.nanolett.7b03695] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The bottom-up fabrication of regular nanowire (NW) arrays on a masked substrate is technologically relevant, but the growth dynamic is rather complex due to the superposition of severe shadowing effects that vary with array pitch, NW diameter, NW height, and growth duration. By inserting GaAsP marker layers at a regular time interval during the growth of a self-catalyzed GaP NW array, we are able to retrieve precisely the time evolution of the diameter and height of a single NW. We then propose a simple numerical scheme which fully computes shadowing effects at play in infinite arrays of NWs. By confronting the simulated and experimental results, we infer that re-emission of Ga from the mask is necessary to sustain the NW growth while Ga migration on the mask must be negligible. When compared to random cosine or random uniform re-emission from the mask, the simple case of specular reflection on the mask gives the most accurate account of the Ga balance during the growth.
Collapse
Affiliation(s)
- Fabrice Oehler
- Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Sud, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France
| | - Andrea Cattoni
- Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Sud, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France
| | - Andrea Scaccabarozzi
- Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Sud, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France
- Institut Photovoltaïque d'Ile-de-France , 92160 Antony, France
| | - Gilles Patriarche
- Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Sud, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France
| | - Frank Glas
- Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Sud, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France
| | - Jean-Christophe Harmand
- Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Sud, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France
| |
Collapse
|
120
|
Abstract
Functional materials and devices require nanoscale control of morphology, crystal structure, and composition. Vapor-liquid-solid (VLS) crystal growth and its related growth modes enable the synthesis of 1D nanostructures, commonly called "nanowires", where the necessary nanoscale heterogeneity can be encoded axially. During the VLS process, a seed particle collects atoms and directs the nucleation of crystalline material. Modulating the delivery of growth species or conditions permits compositional and/or structural encoding. A range of materials and devices (e.g., for electronics, photonics, thermal transport, and bioprobes) have been produced by VLS growth, but plenty of challenges remain: many desirable structures cannot currently be made, and even for those structures that can be made, the parameter window-in terms of, e.g., temperatures and pressures-is often narrow. Moreover, we are quite far from ab initio determination of which growth conditions should be used or even if a desired structure is fundamentally achievable within the VLS framework. To fully understand the challenges and promises of VLS growth, the governing physicochemical processes must be explored and understood at the atomic scale. This final level of detail is being unraveled with the help of in situ characterization techniques. The picture that is emerging is of a highly dynamical process with several deeply interconnected and highly fundamental components that are difficult to detect with postgrowth ex situ interrogation. For example, recent in situ microscopy and spectroscopy studies have shown that the growth front can undergo cyclical reshaping involving dissolution as well as crystallization and that the state of the nanowire surface, which changes with growth conditions as a result of a competition between adsorption and desorption of passivating species, plays a crucial role in determining the transport to/from and the stability of the seed particle. The available in situ observations currently constitute a somewhat disparate list, but if they can be connected to each other and to the outstanding challenges, they promise meaningful advances in our understanding of VLS growth. In this Account, we review the state of the art regarding the atomic-scale thermodynamic and kinetic phenomena that control VLS growth. Rather than cataloging all of the outstanding contributions to the field, we give priority to in situ observations that have revealed unexpected effects as well as those that hint at incongruities in our current knowledge. As such, our discussion should be viewed as an opportunity to gain deeper understanding and control of the fundamental processes at play, which will be crucial in future scale-up efforts and expansion to completely new materials systems and application areas.
Collapse
Affiliation(s)
- Martin Ek
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- Solid
State Physics/NanoLund, Lund University, Box 118, 221 00 Lund, Sweden
| | - Michael A. Filler
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| |
Collapse
|
121
|
Kim W, Dubrovskii VG, Vukajlovic-Plestina J, Tütüncüoglu G, Francaviglia L, Güniat L, Potts H, Friedl M, Leran JB, Fontcuberta I Morral A. Bistability of Contact Angle and Its Role in Achieving Quantum-Thin Self-Assisted GaAs nanowires. NANO LETTERS 2018; 18:49-57. [PMID: 29257895 DOI: 10.1021/acs.nanolett.7b03126] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Achieving quantum confinement by bottom-up growth of nanowires has so far been limited to the ability of obtaining stable metal droplets of radii around 10 nm or less. This is within reach for gold-assisted growth. Because of the necessity to maintain the group III droplets during growth, direct synthesis of quantum sized structures becomes much more challenging for self-assisted III-V nanowires. In this work, we elucidate and solve the challenges that involve the synthesis of gallium-assisted quantum-sized GaAs nanowires. We demonstrate the existence of two stable contact angles for the gallium droplet on top of GaAs nanowires. Contact angle around 130° fosters a continuous increase in the nanowire radius, while 90° allows for the stable growth of ultrathin tops. The experimental results are fully consistent with our model that explains the observed morphological evolution under the two different scenarios. We provide a generalized theory of self-assisted III-V nanowires that describes simultaneously the droplet shape relaxation and the NW radius evolution. Bistability of the contact angle described here should be the general phenomenon that pertains for any vapor-liquid-solid nanowires and significantly refines our picture of how nanowires grow. Overall, our results suggest a new path for obtaining ultrathin one-dimensional III-V nanostructures for studying lateral confinement of carriers.
Collapse
Affiliation(s)
- Wonjong Kim
- Laboratory of Semiconductor Materials, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | | | - Jelena Vukajlovic-Plestina
- Laboratory of Semiconductor Materials, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Gözde Tütüncüoglu
- Laboratory of Semiconductor Materials, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Luca Francaviglia
- Laboratory of Semiconductor Materials, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Lucas Güniat
- Laboratory of Semiconductor Materials, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Heidi Potts
- Laboratory of Semiconductor Materials, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Martin Friedl
- Laboratory of Semiconductor Materials, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Jean-Baptiste Leran
- Laboratory of Semiconductor Materials, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| | - Anna Fontcuberta I Morral
- Laboratory of Semiconductor Materials, Institute of Materials, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland
| |
Collapse
|
122
|
Schroth P, Jakob J, Feigl L, Mostafavi Kashani SM, Vogel J, Strempfer J, Keller TF, Pietsch U, Baumbach T. Radial Growth of Self-Catalyzed GaAs Nanowires and the Evolution of the Liquid Ga-Droplet Studied by Time-Resolved in Situ X-ray Diffraction. NANO LETTERS 2018; 18:101-108. [PMID: 29283268 DOI: 10.1021/acs.nanolett.7b03486] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on a growth study of self-catalyzed GaAs nanowires based on time-resolved in situ X-ray structure characterization during molecular-beam-epitaxy in combination with ex situ scanning-electron-microscopy. We reveal the evolution of nanowire radius and polytypism and distinguish radial growth processes responsible for tapering and side-wall growth. We interpret our results using a model for diameter self-stabilization processes during growth of self-catalyzed GaAs nanowires including the shape of the liquid Ga-droplet and its evolution during growth.
Collapse
Affiliation(s)
- Philipp Schroth
- Solid State Physics, Department of Physics, University of Siegen , Walter-Flex Straße 3, D-57068 Siegen, Germany
- Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology , Kaiserstraße 12, D-76131 Karlsruhe, Germany
- Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology , Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
| | - Julian Jakob
- Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology , Kaiserstraße 12, D-76131 Karlsruhe, Germany
| | - Ludwig Feigl
- Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology , Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
| | | | - Jonas Vogel
- Solid State Physics, Department of Physics, University of Siegen , Walter-Flex Straße 3, D-57068 Siegen, Germany
- Deutsches Elektronen-Synchrotron DESY , Notkestraße 85, D-22607 Hamburg, Germany
| | - Jörg Strempfer
- Deutsches Elektronen-Synchrotron DESY , Notkestraße 85, D-22607 Hamburg, Germany
| | - Thomas F Keller
- Deutsches Elektronen-Synchrotron DESY , Notkestraße 85, D-22607 Hamburg, Germany
- Fachbereich Physik, Universität Hamburg , Jungiusstraße 9, D-20355 Hamburg, Germany
| | - Ullrich Pietsch
- Solid State Physics, Department of Physics, University of Siegen , Walter-Flex Straße 3, D-57068 Siegen, Germany
| | - Tilo Baumbach
- Laboratory for Applications of Synchrotron Radiation, Karlsruhe Institute of Technology , Kaiserstraße 12, D-76131 Karlsruhe, Germany
- Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology , Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
| |
Collapse
|
123
|
Zhang Y, Sun Z, Sanchez AM, Ramsteiner M, Aagesen M, Wu J, Kim D, Jurczak P, Huo S, Lauhon LJ, Liu H. Doping of Self-Catalyzed Nanowires under the Influence of Droplets. NANO LETTERS 2018; 18:81-87. [PMID: 29206466 DOI: 10.1021/acs.nanolett.7b03366] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Controlled and reproducible doping is essential for nanowires (NWs) to realize their functions. However, for the widely used self-catalyzed vapor-liquid-solid (VLS) growth mode, the doping mechanism is far from clear, as the participation of the nanoscale liquid phase makes the doping environment highly complex and significantly different from that of the thin film growth. Here, the doping mechanism of self-catalyzed NWs and the influence of self-catalytic droplets on the doping process are systematically studied using beryllium (Be) doped GaAs NWs. Be atoms are found for the first time to be incorporated into NWs predominantly through the Ga droplet that is observed to be beneficial for setting up thermodynamic equilibrium at the growth front. Be dopants are thus substitutional on Ga sites and redundant Be atoms are accumulated inside the Ga droplets when NWs are saturated, leading to the change of the Ga droplet properties and causing the growth of phase-pure zincblende NWs. This study is an essential step toward the design and fabrication of nanowire devices.
Collapse
Affiliation(s)
- Yunyan Zhang
- Department of Electronic and Electrical Engineering, University College London , London WC1E 7JE, United Kingdom
| | - Zhiyuan Sun
- Department of Materials Science and Engineering, Northwestern University , 2220 Campus Drive, Evanston, Illinois 60208-3108, United States
| | - Ana M Sanchez
- Department of Physics, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Manfred Ramsteiner
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Martin Aagesen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Jiang Wu
- Department of Electronic and Electrical Engineering, University College London , London WC1E 7JE, United Kingdom
| | - Dongyoung Kim
- Department of Electronic and Electrical Engineering, University College London , London WC1E 7JE, United Kingdom
| | - Pamela Jurczak
- Department of Electronic and Electrical Engineering, University College London , London WC1E 7JE, United Kingdom
| | - Suguo Huo
- London Centre for Nanotechnology, University College London , London WC1H 0AH, United Kingdom
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, Northwestern University , 2220 Campus Drive, Evanston, Illinois 60208-3108, United States
| | - Huiyun Liu
- Department of Electronic and Electrical Engineering, University College London , London WC1E 7JE, United Kingdom
| |
Collapse
|
124
|
Zannier V, Rossi F, Dubrovskii VG, Ercolani D, Battiato S, Sorba L. Nanoparticle Stability in Axial InAs-InP Nanowire Heterostructures with Atomically Sharp Interfaces. NANO LETTERS 2018; 18:167-174. [PMID: 29186660 DOI: 10.1021/acs.nanolett.7b03742] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The possibility to expand the range of material combinations in defect-free heterostructures is one of the main motivations for the great interest in semiconductor nanowires. However, most axial nanowire heterostructures suffer from interface compositional gradients and kink formation, as a consequence of nanoparticle-nanowire interactions during the metal-assisted growth. Understanding such interactions and how they affect the growth mode is fundamental to achieve a full control over the morphology and the properties of nanowire heterostructures for device applications. Here we demonstrate that the sole parameter affecting the growth mode (straight or kinked) of InP segments on InAs nanowire stems by the Au-assisted method is the nanoparticle composition. Indeed, straight InAs-InP nanowire heterostructures are obtained only when the In/Au ratio in the nanoparticles is low, typically smaller than 1.5. For higher In content, the InP segments tend to kink. Tailoring the In/Au ratio by the precursor fluxes at a fixed growth temperature enables us to obtain straight and radius-uniform InAs-InP nanowire heterostructures (single and double) with atomically sharp interfaces. We present a model that is capable of describing all the experimentally observed phenomena: straight growth versus kinking, the stationary nanoparticle compositions in pure InAs and InAs-InP nanowires, the crystal phase trends, and the interfacial abruptness. By taking into account different nanowire/nanoparticle interfacial configurations (forming wetting or nonwetting monolayers in vertical or tapered geometry), our generalized model provides the conditions of nanoparticle stability and abrupt heterointerfaces for a rich variety of growth scenarios. Therefore, our results provide a powerful tool for obtaining high quality InAs-InP nanowire heterostructures with well-controlled properties and can be extended to other material combinations based on the group V interchange.
Collapse
Affiliation(s)
- Valentina Zannier
- NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore , Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Francesca Rossi
- IMEM - CNR , Parco Area delle Scienze 37/A, 43124 Parma, Italy
| | - Vladimir G Dubrovskii
- ITMO University , Kronverkskiy Pr. 49, 197101 Saint Petersburg, Russia
- Ioffe Institute RAS , Politekhnicheskaya 26, 194021 Saint Petersburg, Russia
| | - Daniele Ercolani
- NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore , Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Sergio Battiato
- NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore , Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Lucia Sorba
- NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore , Piazza San Silvestro 12, 56127 Pisa, Italy
| |
Collapse
|
125
|
Wu S, Wang L, Yi X, Liu Z, Yan J, Yuan G, Wei T, Wang J, Li J. Crystallographic orientation control and optical properties of GaN nanowires. RSC Adv 2018; 8:2181-2187. [PMID: 35542617 PMCID: PMC9077256 DOI: 10.1039/c7ra11408g] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/01/2018] [Indexed: 11/21/2022] Open
Abstract
The optical and electrical properties of nitride materials are closely related to their crystallographic orientation. Here, we report our effort on crystallographic orientation manipulation of GaN NWs using vapour-liquid-solid hydride vapour phase epitaxy (VLS-HVPE). The growth orientations of the GaN NWs are tuned from the polar c-axis to the non-polar m-axis by simply varying the supply of III precursors on various substrates, including c-, r, m-plane sapphire, (111) silicon and (0001) GaN. By varying the size of the Ni/Au catalyst, we found that the catalyst size has a negligible influence on the growth orientation of GaN NWs. All these demonstrate that the growth orientation of the GaN NWs is dominated by the flow rate of the precursor, regardless of the catalyst size and the substrate adopted. Moreover, the optical properties of GaN NWs were characterized using micro-photoluminescence, revealing that the observed red luminescence band (near 660 nm) is related to the lateral growth of the GaN NWs. The work presented here will advance the understanding of the VLS process of GaN NWs and represents a step forward towards controllable GaN NW growth.
Collapse
Affiliation(s)
- Shaoteng Wu
- College of Materials Sciences and Opto-Electronic Technology, University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China
- Research and Development Center for Semiconductor Lighting, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
- Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application No. 35A Qinghua East Road Beijing 100083 China
- Institute of Semiconductors, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
| | - Liancheng Wang
- Institute of Semiconductors, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
- State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University Changsha Hunan 410083 P. R. China
| | - Xiaoyan Yi
- College of Materials Sciences and Opto-Electronic Technology, University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China
- Research and Development Center for Semiconductor Lighting, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
- Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application No. 35A Qinghua East Road Beijing 100083 China
- Institute of Semiconductors, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
| | - Zhiqiang Liu
- College of Materials Sciences and Opto-Electronic Technology, University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China
- Research and Development Center for Semiconductor Lighting, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
- Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application No. 35A Qinghua East Road Beijing 100083 China
- Institute of Semiconductors, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
| | - Jianchang Yan
- College of Materials Sciences and Opto-Electronic Technology, University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China
- Research and Development Center for Semiconductor Lighting, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
- Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application No. 35A Qinghua East Road Beijing 100083 China
| | - Guodong Yuan
- College of Materials Sciences and Opto-Electronic Technology, University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China
- Research and Development Center for Semiconductor Lighting, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
- Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application No. 35A Qinghua East Road Beijing 100083 China
| | - Tongbo Wei
- College of Materials Sciences and Opto-Electronic Technology, University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China
- Research and Development Center for Semiconductor Lighting, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
- Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application No. 35A Qinghua East Road Beijing 100083 China
| | - Junxi Wang
- College of Materials Sciences and Opto-Electronic Technology, University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China
- Research and Development Center for Semiconductor Lighting, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
- Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application No. 35A Qinghua East Road Beijing 100083 China
| | - Jinmin Li
- College of Materials Sciences and Opto-Electronic Technology, University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China
- Research and Development Center for Semiconductor Lighting, Chinese Academy of Sciences No. 35A Qinghua East Road Beijing 100083 China
- Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application No. 35A Qinghua East Road Beijing 100083 China
| |
Collapse
|
126
|
Wang F, Buhro WE. Role of Precursor-Conversion Chemistry in the Crystal-Phase Control of Catalytically Grown Colloidal Semiconductor Quantum Wires. ACS NANO 2017; 11:12526-12535. [PMID: 29182853 DOI: 10.1021/acsnano.7b06639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Crystal-phase control is one of the most challenging problems in nanowire growth. We demonstrate that, in the solution-phase catalyzed growth of colloidal cadmium telluride (CdTe) quantum wires (QWs), the crystal phase can be controlled by manipulating the reaction chemistry of the Cd precursors and tri-n-octylphosphine telluride (TOPTe) to favor the production of either a CdTe solute or Te, which consequently determines the composition and (liquid or solid) state of the BixCdyTez catalyst nanoparticles. Growth of single-phase (e.g., wurtzite) QWs is achieved only from solid catalysts (y ≪ z) that enable the solution-solid-solid growth of the QWs, whereas the liquid catalysts (y ≈ z) fulfill the solution-liquid-solid growth of the polytypic QWs. Factors that affect the precursor-conversion chemistry are systematically accounted for, which are correlated with a kinetic study of the composition and state of the catalyst nanoparticles to understand the mechanism. This work reveals the role of the precursor-reaction chemistry in the crystal-phase control of catalytically grown colloidal QWs, opening the possibility of growing phase-pure QWs of other compositions.
Collapse
Affiliation(s)
- Fudong Wang
- Department of Chemistry and Institute of Materials Science and Engineering, Washington University , St. Louis, Missouri 63130-4899, United States
| | - William E Buhro
- Department of Chemistry and Institute of Materials Science and Engineering, Washington University , St. Louis, Missouri 63130-4899, United States
| |
Collapse
|
127
|
Controlling bottom-up rapid growth of single crystalline gallium nitride nanowires on silicon. Sci Rep 2017; 7:17942. [PMID: 29263368 PMCID: PMC5738410 DOI: 10.1038/s41598-017-17980-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 12/04/2017] [Indexed: 11/25/2022] Open
Abstract
We report single crystalline gallium nitride nanowire growth from Ni and Ni-Au catalysts on silicon using hydride vapor phase epitaxy. The growth takes place rapidly; efficiency in time is higher than the conventional nanowire growth in metal-organic chemical vapor deposition and thin film growth in molecular beam epitaxy. The effects of V/III ratio and carrier gas flow on growth are discussed regarding surface polarity and sticking coefficient of molecules. The nanowires of gallium nitride exhibit excellent crystallinity with smooth and straight morphology and uniform orientation. The growth mechanism follows self-assembly from both catalysts, where Au acts as a protection from etching during growth enabling the growth of ultra-long nanowires. The photoluminescence of such nanowires are adjustable by tuning the growth parameters to achieve blue emission. The practical range of parameters for mass production of such high crystal quality and uniformity of nanowires is suggested.
Collapse
|
128
|
Zhang BC, Wang H, He L, Zheng CJ, Jie JS, Lifshitz Y, Lee ST, Zhang XH. Centimeter-Long Single-Crystalline Si Nanowires. NANO LETTERS 2017; 17:7323-7329. [PMID: 29185771 DOI: 10.1021/acs.nanolett.7b02967] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The elongation of free-standing one-dimensional (1D) functional nanostructures into lengths above the millimeter range has brought new practical applications as they combine the remarkable properties of nanostructured materials with macroscopic lengths. However, it remains a big challenge to prepare 1D silicon nanostructures, one of the most important 1D nanostructures, with lengths above the millimeter range. Here we report the unprecedented preparation of ultralong single-crystalline Si nanowires with length up to 2 cm, which can function as the smallest active material to facilitate the miniaturization of macroscopic devices. These ultralong Si nanowires with augmented flexibility are of emerging interest for flexible electronics. We also demonstrate the first single-nanowire-based wearable joint motion sensor with superior performance to reported systems, which just represents one example of novel devices that can be built from these nanowires. The preparation of ultralong Si nanowires will stimulate the fabrication and miniaturization of electric, optical, medical, and mechanical devices to impact the semiconductor industry and our daily life in the near future.
Collapse
Affiliation(s)
- Bing-Chang Zhang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials and CityU-CAS Joint Laboratory of Functional Materials and Devices, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory of Carbon-Based Functional Materials and Devices, Soochow University , Suzhou 215123, Jiangsu, People's Republic of China
| | - Hui Wang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials and CityU-CAS Joint Laboratory of Functional Materials and Devices, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
| | - Le He
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory of Carbon-Based Functional Materials and Devices, Soochow University , Suzhou 215123, Jiangsu, People's Republic of China
| | - Cai-Jun Zheng
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials and CityU-CAS Joint Laboratory of Functional Materials and Devices, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
- School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC) , Chengdu 610054, People's Republic of China
| | - Jian-Sheng Jie
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory of Carbon-Based Functional Materials and Devices, Soochow University , Suzhou 215123, Jiangsu, People's Republic of China
| | - Yeshayahu Lifshitz
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory of Carbon-Based Functional Materials and Devices, Soochow University , Suzhou 215123, Jiangsu, People's Republic of China
- Department of Materials Science and Engineering, Technion, Israel Institute of Technology , Haifa 3200003, Israel
| | - Shuit-Tong Lee
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory of Carbon-Based Functional Materials and Devices, Soochow University , Suzhou 215123, Jiangsu, People's Republic of China
| | - Xiao-Hong Zhang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials and CityU-CAS Joint Laboratory of Functional Materials and Devices, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory of Carbon-Based Functional Materials and Devices, Soochow University , Suzhou 215123, Jiangsu, People's Republic of China
| |
Collapse
|
129
|
Meyers JK, Kim S, Hill DJ, Cating EEM, Williams LJ, Kumbhar AS, McBride JR, Papanikolas JM, Cahoon JF. Self-Catalyzed Vapor-Liquid-Solid Growth of Lead Halide Nanowires and Conversion to Hybrid Perovskites. NANO LETTERS 2017; 17:7561-7568. [PMID: 29111750 DOI: 10.1021/acs.nanolett.7b03514] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Lead halide perovskites (LHPs) have shown remarkable promise for use in photovoltaics, photodetectors, light-emitting diodes, and lasers. Although solution-processed polycrystalline films are the most widely studied morphology, LHP nanowires (NWs) grown by vapor-phase processes offer the potential for precise control over crystallinity, phase, composition, and morphology. Here, we report the first demonstration of self-catalyzed vapor-liquid-solid (VLS) growth of lead halide (PbX2; X = Cl, Br, or I) NWs and conversion to LHP. We present a kinetic model of the PbX2 NW growth process in which a liquid Pb catalyst is supersaturated with halogen X through vapor-phase incorporation of both Pb and X, inducing growth of a NW. For PbI2, we show that the NWs are single-crystalline, oriented in the ⟨1̅21̅0⟩ direction, and composed of a stoichiometric PbI2 shaft with a spherical Pb tip. Low-temperature vapor-phase intercalation of methylammonium iodide converts the NWs to methylammonium lead iodide (MAPbI3) perovskite while maintaining the NW morphology. Single-NW experiments comparing measured extinction spectra with optical simulations show that the NWs exhibit a strong optical antenna effect, leading to substantially enhanced scattering efficiencies and to absorption efficiencies that can be more than twice that of thin films of the same thickness. Further development of the self-catalyzed VLS mechanism for lead halide and perovskite NWs should enable the rational design of nanostructures for various optoelectronic technologies, including potentially unique applications such as hot-carrier solar cells.
Collapse
Affiliation(s)
| | | | | | | | | | | | - James R McBride
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States
| | | | | |
Collapse
|
130
|
Himwas C, Collin S, Rale P, Chauvin N, Patriarche G, Oehler F, Julien FH, Travers L, Harmand JC, Tchernycheva M. In situ passivation of GaAsP nanowires. NANOTECHNOLOGY 2017; 28:495707. [PMID: 29057754 DOI: 10.1088/1361-6528/aa9533] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the structural and optical properties of GaAsP nanowires (NWs) grown by molecular-beam epitaxy. By adjusting the alloy composition in the NWs, the transition energy was tuned to the optimal value required for tandem III-V/silicon solar cells. We discovered that an unintentional shell was also formed during the GaAsP NW growth. The NW surface was passivated by an in situ deposition of a radial Ga(As)P shell. Different shell compositions and thicknesses were investigated. We demonstrate that the optimal passivation conditions for GaAsP NWs (with a gap of 1.78 eV) are obtained with a 5 nm thick GaP shell. This passivation enhances the luminescence intensity of the NWs by 2 orders of magnitude and yields a longer luminescence decay. The luminescence dynamics changes from single exponential decay with a 4 ps characteristic time in non-passivated NWs to a bi-exponential decay with characteristic times of 85 and 540 ps in NWs with GaP shell passivation.
Collapse
Affiliation(s)
- C Himwas
- Centre de Nanosciences et de Nanotechnologies-site Orsay, UMR 9001 CNRS, Univ. Paris Sud, Univ. Paris-Saclay, Bât 220, rue André Ampère, F-91405 Orsay, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
131
|
Lord AM, Ramasse QM, Kepaptsoglou DM, Periwal P, Ross FM, Wilks SP. Stability of Schottky and Ohmic Au Nanocatalysts to ZnO Nanowires. NANO LETTERS 2017; 17:6626-6636. [PMID: 29024594 DOI: 10.1021/acs.nanolett.7b02561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Manufacturable nanodevices must now be the predominant goal of nanotechnological research to ensure the enhanced properties of nanomaterials can be fully exploited and fulfill the promise that fundamental science has exposed. Here, we test the electrical stability of Au nanocatalyst-ZnO nanowire contacts to determine the limits of the electrical transport properties and the metal-semiconductor interfaces. While the transport properties of as-grown Au nanocatalyst contacts to ZnO nanowires have been well-defined, the stability of the interfaces over lengthy time periods and the electrical limits of the ohmic or Schottky function have not been studied. In this work, we use a recently developed iterative analytical process that directly correlates multiprobe transport measurements with subsequent aberration-corrected scanning transmission electron microscopy to study the electrical, structural, and chemical properties when the nanowires are pushed to their electrical limits and show structural changes occur at the metal-nanowire interface or at the nanowire midshaft. The ohmic contacts exhibit enhanced quantum-mechanical edge-tunneling transport behavior because of additional native semiconductor material at the contact edge due to a strong metal-support interaction. The low-resistance nature of the ohmic contacts leads to catastrophic breakdown at the middle of the nanowire span where the maximum heating effect occurs. Schottky-type Au-nanowire contacts are observed when the nanowires are in the as-grown pristine state and display entirely different breakdown characteristics. The higher-resistance rectifying I-V behavior degrades as the current is increased which leads to a permanent weakening of the rectifying effect and atomic-scale structural changes at the edge of the Au interface where the tunneling current is concentrated. Furthermore, to study modified nanowires such as might be used in devices the nanoscale tunneling path at the interface edge of the ohmic nanowire contacts is removed with a simple etch treatment and the nanowires show similar I-V characteristics during breakdown as the Schottky pristine contacts. Breakdown is shown to occur either at the nanowire midshaft or at the Au contact depending on the initial conductivity of the Au contact interface. These results demonstrate the Au-nanowire structures are capable of withstanding long periods of electrical stress and are stable at high current densities ensuring they are ideal components for nanowire-device designs while providing the flexibility of choosing the electrical transport properties which other Au-nanowire systems cannot presently deliver.
Collapse
Affiliation(s)
- Alex M Lord
- Centre for NanoHealth, College of Engineering, University of Swansea , Singleton Park SA2 8PP, United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, United Kingdom
| | - Despoina M Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD, United Kingdom
| | - Priyanka Periwal
- Department of Electrical Engineering, University of Cambridge , Cambridge CB0 3FA, United Kingdom
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States of America
| | - Frances M Ross
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States of America
| | - Steve P Wilks
- Multidisciplinary Nanotechnology Centre, Department of Physics, College of Science, University of Swansea , Singleton Park, SA2 8PP, United Kingdom
| |
Collapse
|
132
|
A Thermodynamic Model of Diameter- and Temperature-dependent Semiconductor Nanowire Growth. Sci Rep 2017; 7:15029. [PMID: 29118428 PMCID: PMC5678082 DOI: 10.1038/s41598-017-15077-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 09/20/2017] [Indexed: 11/17/2022] Open
Abstract
Creating and manipulating nanowires (NWs) with controllable growth direction and crystal orientation is important to meeting the urgent demands of emerging applications with designed properties. Revealing the underlying mechanisms of the experimentally demonstrated effects of NW diameter and growth temperature on growth direction is crucial for applications. Here, we establish a thermodynamic model to clarify the dependence of NW growth direction on diameter and temperature via the vapor-liquid-solid growth mechanism, enabling analysis of NW critical length between unstable and stable states. At a small critical length, NWs with a large diameter or grown at low temperature tend to grow along the <111> direction, while at a large critical length, NWs with a small diameter or grown at high temperature favor the <110> direction. Specific growth parameters of ZnSe NW have been obtained which can guide the design of functional NWs for applications.
Collapse
|
133
|
Kilpi OP, Svensson J, Wu J, Persson AR, Wallenberg R, Lind E, Wernersson LE. Vertical InAs/InGaAs Heterostructure Metal-Oxide-Semiconductor Field-Effect Transistors on Si. NANO LETTERS 2017; 17:6006-6010. [PMID: 28873310 DOI: 10.1021/acs.nanolett.7b02251] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
III-V compound semiconductors offer a path to continue Moore's law due to their excellent electron transport properties. One major challenge, integrating III-V's on Si, can be addressed by using vapor-liquid-solid grown vertical nanowires. InAs is an attractive material due to its superior mobility, although InAs metal-oxide-semiconductor field-effect transistors (MOSFETs) typically suffer from band-to-band tunneling caused by its narrow band gap, which increases the off-current and therefore the power consumption. In this work, we present vertical heterostructure InAs/InGaAs nanowire MOSFETs with low off-currents provided by the wider band gap material on the drain side suppressing band-to-band tunneling. We demonstrate vertical III-V MOSFETs achieving off-current below 1 nA/μm while still maintaining on-performance comparable to InAs MOSFETs; therefore, this approach opens a path to address not only high-performance applications but also Internet-of-Things applications that require low off-state current levels.
Collapse
Affiliation(s)
- Olli-Pekka Kilpi
- Department of Electrical and Information Technology, Lund University , Box 118, 221 00 Lund, Sweden
| | - Johannes Svensson
- Department of Electrical and Information Technology, Lund University , Box 118, 221 00 Lund, Sweden
| | - Jun Wu
- Department of Electrical and Computer Engineering, University of California , Santa Barbara, California 93106, United States
| | - Axel R Persson
- Centre for Analysis and Synthesis, Lund University , Box 124, 221 00 Lund, Sweden
- NanoLund, Lund University , Box 118, 22100 Lund, Sweden
| | - Reine Wallenberg
- Centre for Analysis and Synthesis, Lund University , Box 124, 221 00 Lund, Sweden
- NanoLund, Lund University , Box 118, 22100 Lund, Sweden
| | - Erik Lind
- Department of Electrical and Information Technology, Lund University , Box 118, 221 00 Lund, Sweden
| | - Lars-Erik Wernersson
- Department of Electrical and Information Technology, Lund University , Box 118, 221 00 Lund, Sweden
| |
Collapse
|
134
|
Dastjerdi MHT, Fiordaliso EM, Leshchenko ED, Akhtari-Zavareh A, Kasama T, Aagesen M, Dubrovskii VG, LaPierre RR. Three-fold Symmetric Doping Mechanism in GaAs Nanowires. NANO LETTERS 2017; 17:5875-5882. [PMID: 28903563 DOI: 10.1021/acs.nanolett.7b00794] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A new dopant incorporation mechanism in Ga-assisted GaAs nanowires grown by molecular beam epitaxy is reported. Off-axis electron holography revealed that p-type Be dopants introduced in situ during molecular beam epitaxy growth of the nanowires were distributed inhomogeneously in the nanowire cross-section, perpendicular to the growth direction. The active dopants showed a remarkable azimuthal distribution along the (111)B flat top of the nanowires, which is attributed to preferred incorporation along 3-fold symmetric truncated facets under the Ga droplet. A diffusion model is presented to explain the unique radial and azimuthal variation of the active dopants in the GaAs nanowires.
Collapse
Affiliation(s)
- M H T Dastjerdi
- Department of Engineering Physics, Centre for Emerging Device Technologies, McMaster University , Hamilton, Ontario Canada , L8S 4L7
| | - E M Fiordaliso
- Center for Electron Nanoscopy, Technical University of Denmark , DK-2800 Kongens Lyngby, Denmark
| | - E D Leshchenko
- ITMO University , Kronverkskiy pr. 49, 197101 St. Petersburg, Russia
| | - A Akhtari-Zavareh
- Department of Engineering Physics, Centre for Emerging Device Technologies, McMaster University , Hamilton, Ontario Canada , L8S 4L7
| | - T Kasama
- Center for Electron Nanoscopy, Technical University of Denmark , DK-2800 Kongens Lyngby, Denmark
| | - M Aagesen
- Gasp Solar ApS, Gregersensvej 7, DK-2630 Taastrup, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark
| | - V G Dubrovskii
- ITMO University , Kronverkskiy pr. 49, 197101 St. Petersburg, Russia
- St. Petersburg Academic University , Khlopina 8/3, 194021 St. Petersburg, Russia
- Ioffe Physical Technical Institute of the Russian Academy of Sciences , Politekhnicheskaya 26, 194021 St. Petersburg, Russia
| | - R R LaPierre
- Department of Engineering Physics, Centre for Emerging Device Technologies, McMaster University , Hamilton, Ontario Canada , L8S 4L7
- ITMO University , Kronverkskiy pr. 49, 197101 St. Petersburg, Russia
| |
Collapse
|
135
|
Imaging Atomic Scale Dynamics on III-V Nanowire Surfaces During Electrical Operation. Sci Rep 2017; 7:12790. [PMID: 28986546 PMCID: PMC5630597 DOI: 10.1038/s41598-017-13007-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 09/12/2017] [Indexed: 11/08/2022] Open
Abstract
As semiconductor electronics keep shrinking, functionality depends on individual atomic scale surface and interface features that may change as voltages are applied. In this work we demonstrate a novel device platform that allows scanning tunneling microscopy (STM) imaging with atomic scale resolution across a device simultaneously with full electrical operation. The platform presents a significant step forward as it allows STM to be performed everywhere on the device surface and high temperature processing in reactive gases of the complete device. We demonstrate the new method through proof of principle measurements on both InAs and GaAs nanowire devices with variable biases up to 4 V. On InAs nanowires we observe a surprising removal of atomic defects and smoothing of the surface morphology under applied bias, in contrast to the expected increase in defects and electromigration-related failure. As we use only standard fabrication and scanning instrumentation our concept is widely applicable and opens up the possibility of fundamental investigations of device surface reliability as well as new electronic functionality based on restructuring during operation.
Collapse
|
136
|
Grieb T, Krause FF, Mahr C, Zillmann D, Müller-Caspary K, Schowalter M, Rosenauer A. Optimization of NBED simulations for disc-detection measurements. Ultramicroscopy 2017; 181:50-60. [DOI: 10.1016/j.ultramic.2017.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 03/28/2017] [Accepted: 04/28/2017] [Indexed: 10/19/2022]
|
137
|
Beznasyuk DV, Robin E, Hertog MD, Claudon J, Hocevar M. Dislocation-free axial InAs-on-GaAs nanowires on silicon. NANOTECHNOLOGY 2017; 28:365602. [PMID: 28671871 DOI: 10.1088/1361-6528/aa7d40] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the growth of axial InAs-on-GaAs nanowire heterostructures on silicon by molecular beam epitaxy using 20 nm diameter Au catalysts. First, the growth parameters of the GaAs nanowire segment were optimized to achieve a pure wurtzite crystal structure. Then, we developed a two-step growth procedure to enhance the yield of vertical InAs-on-GaAs nanowires. We achieved 90% of straight InAs-on-GaAs nanowires by further optimizing the growth parameters. We investigated the composition change at the interface by energy dispersive x-ray spectroscopy and the nanowire crystal structure by transmission electron microscopy. The composition of the nominal InAs segment is found to be In x Ga1-x As with x = 0.85 and corresponds to 6% of lattice mismatch with GaAs. Strain mapping performed by the geometrical phase analysis of high-resolution images revealed a dislocation-free GaAs/In0.85Ga0.15As interface. In conclusion, we successfully fabricated highly mismatched heterostructures, confirming the prediction that axial GaAs/In0.85Ga0.15As interfaces are pseudomorphic in nanowires with a diameter smaller than 40 nm.
Collapse
Affiliation(s)
- Daria V Beznasyuk
- Université Grenoble-Alpes, F-38000 Grenoble, France. CNRS-Institut Néel, 25 av. des Martyrs, F-38000 Grenoble, France
| | | | | | | | | |
Collapse
|
138
|
Sun Z, Seidman DN, Lauhon LJ. Nanowire Kinking Modulates Doping Profiles by Reshaping the Liquid-Solid Growth Interface. NANO LETTERS 2017; 17:4518-4525. [PMID: 28658572 DOI: 10.1021/acs.nanolett.7b02071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Dopants modify the electronic properties of semiconductors, including their susceptibility to etching. In semiconductor nanowires doped during growth by the vapor-liquid-solid (VLS) process, it has been shown that nanofaceting of the liquid-solid growth interface influences strongly the radial distribution of dopants. Hence, the combination of facet-dependent doping and dopant selective etching provides a means to tune simultaneously the electronic properties and morphologies of nanowires. Using atom-probe tomography, we investigated the boron dopant distribution in Au catalyzed VLS grown silicon nanowires, which regularly kink between equivalent ⟨112⟩ directions. Segments alternate between radially uniform and nonuniform doping profiles, which we attribute to switching between a concave and convex faceted liquid-solid interface. Dopant selective etching was used to reveal and correlate the shape of the growth interface with the observed anisotropic doping.
Collapse
Affiliation(s)
- Zhiyuan Sun
- Department of Materials Science and Engineering, Northwestern University , 2220 Campus Drive, Evanston, Illinois 60208-3108, United States
| | - David N Seidman
- Department of Materials Science and Engineering, Northwestern University , 2220 Campus Drive, Evanston, Illinois 60208-3108, United States
- Northwestern University Center for Atom-Probe Tomography (NUCAPT) , 2220 Campus Drive, Evanston, Illinois 60208-3108, United States
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, Northwestern University , 2220 Campus Drive, Evanston, Illinois 60208-3108, United States
| |
Collapse
|
139
|
Zhang Z, Sheng L, Chen L, Zhang Z, Wang Y. Atomic-scale observation of pressure-dependent reduction dynamics of W 18O 49 nanowires using environmental TEM. Phys Chem Chem Phys 2017; 19:16307-16311. [PMID: 28608883 DOI: 10.1039/c7cp03071a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The real-time observation of structural evolution of materials can provide critical information for understanding their reduction mechanisms under different environments. Herein, we report the atomic-scale observation of the reduction dynamics of W18O49 nanowires (NWs) using environmental transmission electron microscopy. Intriguingly, the reduction pathway is found to be affected by oxygen pressure. Under high oxygen pressure (∼0.095 Pa), a W18O49 NW epitaxially transforms into a WO2 NW via mass transport across the interface between (010)W18O49 and (101)WO2. While under low oxygen pressure (∼0.0004 Pa), the transformation follows the sequence of W18O49(NW) → WO2(NW) → β-W(nanoparticles), which is identified as a new reduction pathway. These findings reveal the pressure-dependent reduction and a new transformation pathway, and extend our current understanding of the reduction dynamics of metal oxides.
Collapse
Affiliation(s)
- Zhengfei Zhang
- Center of Electron Microscopy and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China.
| | | | | | | | | |
Collapse
|
140
|
Steinhauer S, Vernieres J, Krainer J, Köck A, Grammatikopoulos P, Sowwan M. In situ chemoresistive sensing in the environmental TEM: probing functional devices and their nanoscale morphology. NANOSCALE 2017; 9:7380-7384. [PMID: 28387407 DOI: 10.1039/c6nr09322a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In situ transmission electron microscopy provides exciting opportunities to address fundamental questions and technological aspects related to functional nanomaterials, including the structure-property relationships of miniaturized electronic devices. Herein, we report the in situ chemoresistive sensing in the environmental transmission electron microscope (TEM) with a single SnO2 nanowire device, studying the impact of surface functionalization with heterogeneous nanocatalysts. By detecting toxic carbon monoxide (CO) gas at ppm-level concentrations inside the microscope column, the sensing properties of a single SnO2 nanowire were characterized before and after decoration with hybrid Fe-Pd nanocubes. The structural changes of the supported nanoparticles induced by sensor operation were revealed, enabling direct correlation with CO sensing properties. Our novel approach is applicable for a broad range of functional nanomaterials and paves the way for future studies on the relationship between chemoresistive properties and nanoscale morphology.
Collapse
Affiliation(s)
- Stephan Steinhauer
- Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, 1919-1 Tancha, Onna-Son, Okinawa 904-0495, Japan.
| | | | | | | | | | | |
Collapse
|
141
|
Behrens SH, Breedveld V, Mujica M, Filler MA. Process Principles for Large-Scale Nanomanufacturing. Annu Rev Chem Biomol Eng 2017; 8:201-226. [PMID: 28375773 DOI: 10.1146/annurev-chembioeng-060816-101522] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Nanomanufacturing—the fabrication of macroscopic products from well-defined nanoscale building blocks—in a truly scalable and versatile manner is still far from our current reality. Here, we describe the barriers to large-scale nanomanufacturing and identify routes to overcome them. We argue for nanomanufacturing systems consisting of an iterative sequence of synthesis/assembly and separation/sorting unit operations, analogous to those used in chemicals manufacturing. In addition to performance and economic considerations, phenomena unique to the nanoscale must guide the design of each unit operation and the overall process flow. We identify and discuss four key nanomanufacturing process design needs: (a) appropriately selected process break points, (b) synthesis techniques appropriate for large-scale manufacturing, (c) new structure- and property-based separations, and (d) advances in stabilization and packaging.
Collapse
Affiliation(s)
- Sven H. Behrens
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0100
| | - Victor Breedveld
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0100
| | - Maritza Mujica
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0100
| | - Michael A. Filler
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0100
| |
Collapse
|
142
|
Sanchez AM, Zhang Y, Tait EW, Hine NDM, Liu H, Beanland R. Nonradiative Step Facets in Semiconductor Nanowires. NANO LETTERS 2017; 17:2454-2459. [PMID: 28337920 DOI: 10.1021/acs.nanolett.7b00123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
One of the main advantages of nanowires for functional applications is their high perfection, which results from surface image forces that act on line defects such as dislocations, rendering them unstable and driving them out of the crystal. Here we show that there is a class of step facets that are stable in nanowires, with no long-range strain field or dislocation character. In zinc-blende semiconductors, they take the form of Σ3 (112) facets with heights constrained to be a multiple of three {111} monolayers. Density functional theory calculations show that they act as nonradiative recombination centers and have deleterious effects on nanowire properties. We present experimental observations of these defects on twin boundaries and twins that terminate inside GaAsP nanowires and find that they are indeed always multiples of three monolayers in height. Strategies to use the three-monolayer rule during growth to prevent their formation are discussed.
Collapse
Affiliation(s)
- Ana M Sanchez
- Department of Physics, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Yunyan Zhang
- Department of Electronic and Electrical Engineering, University College London , Torrington Place, London WC1E 7JE, United Kingdom
| | - Edward W Tait
- TCM Group, Cavendish Laboratory , 19 JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom
| | - Nicholas D M Hine
- Department of Physics, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Huiyun Liu
- Department of Electronic and Electrical Engineering, University College London , Torrington Place, London WC1E 7JE, United Kingdom
| | - Richard Beanland
- Department of Physics, University of Warwick , Coventry CV4 7AL, United Kingdom
| |
Collapse
|
143
|
Potts H, Morgan NP, Tütüncüoglu G, Friedl M, Morral AFI. Tuning growth direction of catalyst-free InAs(Sb) nanowires with indium droplets. NANOTECHNOLOGY 2017; 28:054001. [PMID: 28008881 DOI: 10.1088/1361-6528/28/5/054001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The need for indium droplets to initiate self-catalyzed growth of InAs nanowires has been highly debated in the last few years. Here, we report on the use of indium droplets to tune the growth direction of self-catalyzed InAs nanowires. The indium droplets are formed in situ on InAs(Sb) stems. Their position is modified to promote growth in the 〈11-2〉 or equivalent directions. We also show that indium droplets can be used for the fabrication of InSb insertions in InAsSb nanowires. Our results demonstrate that indium droplets can initiate growth of InAs nanostructures as well as provide added flexibility to nanowire growth, enabling the formation of kinks and heterostructures, and offer a new approach in the growth of defect-free crystals.
Collapse
Affiliation(s)
- Heidi Potts
- Laboratoire des Matériaux Semiconducteurs, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | | | | | | | | |
Collapse
|
144
|
Gagliano L, Belabbes A, Albani M, Assali S, Verheijen MA, Miglio L, Bechstedt F, Haverkort JEM, Bakkers EPAM. Pseudodirect to Direct Compositional Crossover in Wurtzite GaP/In xGa 1-xP Core-Shell Nanowires. NANO LETTERS 2016; 16:7930-7936. [PMID: 27960532 DOI: 10.1021/acs.nanolett.6b04242] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Thanks to their uniqueness, nanowires allow the realization of novel semiconductor crystal structures with yet unexplored properties, which can be key to overcome current technological limits. Here we develop the growth of wurtzite GaP/InxGa1-xP core-shell nanowires with tunable indium concentration and optical emission in the visible region from 590 nm (2.1 eV) to 760 nm (1.6 eV). We demonstrate a pseudodirect (Γ8c-Γ9v) to direct (Γ7c-Γ9v) transition crossover through experimental and theoretical approach. Time resolved and temperature dependent photoluminescence measurements were used, which led to the observation of a steep change in carrier lifetime and temperature dependence by respectively one and 3 orders of magnitude in the range 0.28 ± 0.04 ≤ x ≤ 0.41 ± 0.04. Our work reveals the electronic properties of wurtzite InxGa1-xP.
Collapse
Affiliation(s)
- L Gagliano
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - A Belabbes
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia
- Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universitat , Max-Wien-Platz 1, D-07743 Jena, Germany
| | - M Albani
- L-NESS and Department of Materials Science, University of Milano Bicocca , 20125, Milano, Italy
| | - S Assali
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - M A Verheijen
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Philips Innovation Laboratories Eindhoven , High Tech Campus 11, 5656AE Eindhoven, The Netherlands
| | - L Miglio
- L-NESS and Department of Materials Science, University of Milano Bicocca , 20125, Milano, Italy
| | - F Bechstedt
- Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universitat , Max-Wien-Platz 1, D-07743 Jena, Germany
| | - J E M Haverkort
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - E P A M Bakkers
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
| |
Collapse
|
145
|
Zannier V, Ercolani D, Gomes UP, David J, Gemmi M, Dubrovskii VG, Sorba L. Catalyst Composition Tuning: The Key for the Growth of Straight Axial Nanowire Heterostructures with Group III Interchange. NANO LETTERS 2016; 16:7183-7190. [PMID: 27760298 DOI: 10.1021/acs.nanolett.6b03524] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Au-catalyzed III-V nanowire heterostructures based on the group III interchange usually grow straight only in one of the two growth sequences, whereas the other sequence produces kinked geometries; thus, the realization of double heterostructures remains challenging. Here, we investigate the growth of Au-assisted InAs-GaAs and GaAs-InAs axial nanowire heterostructures. A detailed study of the heterostructure morphology as a function of growth parameters and chemical composition of the catalyst nanoparticle is performed by means of scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray analysis. Our results clearly demonstrate that the nanoparticle composition, rather than other growth parameters, as postulated so far, controls the growth mode and the resulting nanowire morphology. Although GaAs easily grows straight on InAs, straight growth of InAs on GaAs is achieved only if the nanoparticle composition is properly tuned. We find that straight InAs segments on GaAs require high group III-to-Au ratios in the nanoparticle (greater than 0.8); otherwise, the droplet wets the sidewalls and the nanowire kinks. We discuss the observed behavior within a theoretical model that relates the nanoparticle stability to the group III-to-Au ratio. Based on this finding, we demonstrate the growth of straight nanowire heterostructures for both sequences. The proposed strategy can be extended to other III-V nanowire heterostructures based on the group III interchange, allowing for straight morphology regardless of the growth sequence, and ultimately for designing nanowire heterostructures with the required properties for different applications.
Collapse
Affiliation(s)
- Valentina Zannier
- NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore , Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Daniele Ercolani
- NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore , Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Umesh Prasad Gomes
- NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore , Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Jérémy David
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia , Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Mauro Gemmi
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia , Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Vladimir G Dubrovskii
- St. Petersburg Academic University , Khlopina 8/3, 194021 Saint Petersburg, Russia
- ITMO University , Kronverkskiy Prospekt 49, 197101 Saint Petersburg, Russia
| | - Lucia Sorba
- NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore , Piazza San Silvestro 12, 56127 Pisa, Italy
| |
Collapse
|
146
|
Sivaram SV, Hui HY, de la Mata M, Arbiol J, Filler MA. Surface Hydrogen Enables Subeutectic Vapor-Liquid-Solid Semiconductor Nanowire Growth. NANO LETTERS 2016; 16:6717-6723. [PMID: 27347747 DOI: 10.1021/acs.nanolett.6b01640] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Vapor-liquid-solid nanowire growth below the bulk metal-semiconductor eutectic temperature is known for several systems; however, the fundamental processes that govern this behavior are poorly understood. Here, we show that hydrogen atoms adsorbed on the Ge nanowire sidewall enable AuGe catalyst supercooling and control Au transport. Our approach combines in situ infrared spectroscopy to directly and quantitatively determine hydrogen atom coverage with a "regrowth" step that allows catalyst phase to be determined with ex situ electron microscopy. Maintenance of a supercooled catalyst with only hydrogen radical delivery confirms the centrality of sidewall chemistry. This work underscores the importance of the nanowire sidewall and its chemistry on catalyst state, identifies new methods to regulate catalyst composition, and provides synthetic strategies for subeutectic growth in other nanowire systems.
Collapse
Affiliation(s)
- Saujan V Sivaram
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Ho Yee Hui
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - María de la Mata
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology , Campus UAB, Bellaterra, Barcelona, Catalonia 08193, Spain
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology , Campus UAB, Bellaterra, Barcelona, Catalonia 08193, Spain
| | - Michael A Filler
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| |
Collapse
|
147
|
Pinion CW, Hill DJ, Christesen JD, McBride JR, Cahoon JF. Barrierless Switching between a Liquid and Superheated Solid Catalyst during Nanowire Growth. J Phys Chem Lett 2016; 7:4236-4242. [PMID: 27717285 DOI: 10.1021/acs.jpclett.6b01918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Knowledge of nucleation and growth mechanisms is essential for the synthesis of nanomaterials, such as semiconductor nanowires, with shapes and compositions precisely engineered for technological applications. Nanowires are conventionally grown by the seemingly well-understood vapor-liquid-solid mechanism, which uses a liquid alloy as the catalyst for growth. However, we show that it is possible to instantaneously and reversibly switch the phase of the catalyst between a liquid and superheated solid state under isothermal conditions above the eutectic temperature. The solid catalyst induces a vapor-solid-solid growth mechanism, which provides atomic-level control of dopant atoms in the nanowire. The switching effect cannot be predicted from equilibrium phase diagrams but can be explained by the dominant role of the catalyst surface in modulating the kinetics and thermodynamics of phase behavior. The effect should be general to metal-catalyzed nanowire growth and highlights the unexpected yet technologically relevant nonequilibrium effects that can emerge in the growth of nanoscale systems.
Collapse
Affiliation(s)
- Christopher W Pinion
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - David J Hill
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - Joseph D Christesen
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| | - James R McBride
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - James F Cahoon
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
| |
Collapse
|
148
|
Timofeeva M, Bouravleuv A, Cirlin G, Shtrom I, Soshnikov I, Reig Escalé M, Sergeyev A, Grange R. Polar Second-Harmonic Imaging to Resolve Pure and Mixed Crystal Phases along GaAs Nanowires. NANO LETTERS 2016; 16:6290-6297. [PMID: 27657488 DOI: 10.1021/acs.nanolett.6b02592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In this work, we report an optical method for characterizing crystal phases along single-semiconductor III-V nanowires based on the measurement of polarization-dependent second-harmonic generation. This powerful imaging method is based on a per-pixel analysis of the second-harmonic-generated signal on the incoming excitation polarization. The dependence of the second-harmonic generation responses on the nonlinear second-order susceptibility tensor allows the distinguishing of areas of pure wurtzite, zinc blende, and mixed and rotational twins crystal structures in individual nanowires. With a far-field nonlinear optical microscope, we recorded the second-harmonic generation in GaAs nanowires and precisely determined their various crystal structures by analyzing the polar response for each pixel of the images. The predicted crystal phases in GaAs nanowire are confirmed with scanning transmission electron and high-resolution transmission electron measurements. The developed method of analyzing the nonlinear polar response of each pixel can be used for an investigation of nanowire crystal structure that is quick, sensitive to structural transitions, nondestructive, and on-the-spot. It can be applied for the crystal phase characterization of nanowires built into optoelectronic devices in which electron microscopy cannot be performed (for example, in lab-on-a-chip devices). Moreover, this method is not limited to GaAs nanowires but can be used for other nonlinear optical nanostructures.
Collapse
Affiliation(s)
- Maria Timofeeva
- Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics, ETH Zurich , Auguste-Piccard Hof 1, 8093 Zurich, Switzerland
- ITMO University , Kronverkskiy 49, 197101 Saint Petersburg, Russia
| | - Alexei Bouravleuv
- St. Petersburg Academic University , Khlopina 8/3, 194021 Saint Petersburg, Russia
- Ioffe Institute , Politekhnicheskaya 29, 194021 Saint Petersburg, Russia
| | - George Cirlin
- St. Petersburg Academic University , Khlopina 8/3, 194021 Saint Petersburg, Russia
- ITMO University , Kronverkskiy 49, 197101 Saint Petersburg, Russia
- Ioffe Institute , Politekhnicheskaya 29, 194021 Saint Petersburg, Russia
| | - Igor Shtrom
- St. Petersburg Academic University , Khlopina 8/3, 194021 Saint Petersburg, Russia
- Ioffe Institute , Politekhnicheskaya 29, 194021 Saint Petersburg, Russia
| | - Ilya Soshnikov
- St. Petersburg Academic University , Khlopina 8/3, 194021 Saint Petersburg, Russia
- Ioffe Institute , Politekhnicheskaya 29, 194021 Saint Petersburg, Russia
| | - Marc Reig Escalé
- Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics, ETH Zurich , Auguste-Piccard Hof 1, 8093 Zurich, Switzerland
| | - Anton Sergeyev
- Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics, ETH Zurich , Auguste-Piccard Hof 1, 8093 Zurich, Switzerland
| | - Rachel Grange
- Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics, ETH Zurich , Auguste-Piccard Hof 1, 8093 Zurich, Switzerland
| |
Collapse
|
149
|
Metaferia W, Persson AR, Mergenthaler K, Yang F, Zhang W, Yartsev A, Wallenberg R, Pistol ME, Deppert K, Samuelson L, Magnusson MH. GaAsP Nanowires Grown by Aerotaxy. NANO LETTERS 2016; 16:5701-5707. [PMID: 27564139 DOI: 10.1021/acs.nanolett.6b02367] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have grown GaAsP nanowires with high optical and structural quality by Aerotaxy, a new continuous gas phase mass production process to grow III-V semiconductor based nanowires. By varying the PH3/AsH3 ratio and growth temperature, size selected GaAs1-xPx nanowires (80 nm diameter) with pure zinc-blende structure and with direct band gap energies ranging from 1.42 to 1.90 eV (at 300 K), (i.e., 0 ≤ x ≤ 0.43) were grown, which is the energy range needed for creating tandem III-V solar cells on silicon. The phosphorus content in the NWs is shown to be controlled by both growth temperature and input gas phase ratio. The distribution of P in the wires is uniform over the length of the wires and among the wires. This proves the feasibility of growing GaAsP nanowires by Aerotaxy and results indicate that it is a generic process that can be applied to the growth of other III-V semiconductor based ternary nanowires.
Collapse
Affiliation(s)
- Wondwosen Metaferia
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Axel R Persson
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Kilian Mergenthaler
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Fangfang Yang
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Wei Zhang
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Arkady Yartsev
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Reine Wallenberg
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Mats-Erik Pistol
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Knut Deppert
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Lars Samuelson
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| | - Martin H Magnusson
- NanoLund and ‡Solid State Physics, Lund University , Box 118, SE-22100 Lund, Sweden
- nCHREM/Centre for Analysis and Synthesis and ∥Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden
| |
Collapse
|
150
|
Amato M, Kaewmaraya T, Zobelli A, Palummo M, Rurali R. Crystal Phase Effects in Si Nanowire Polytypes and Their Homojunctions. NANO LETTERS 2016; 16:5694-5700. [PMID: 27530077 DOI: 10.1021/acs.nanolett.6b02362] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recent experimental investigations have confirmed the possibility to synthesize and exploit polytypism in group IV nanowires. Driven by this promising evidence, we use first-principles methods based on density functional theory and many-body perturbation theory to investigate the electronic and optical properties of hexagonal-diamond and cubic-diamond Si NWs as well as their homojunctions. We show that hexagonal-diamond NWs are characterized by a more pronounced quantum confinement effect than cubic-diamond NWs. Furthermore, they absorb more light in the visible region with respect to cubic-diamond ones and, for most of the studied diameters, they are direct band gap materials. The study of the homojunctions reveals that the diameter has a crucial effect on the band alignment at the interface. In particular, at small diameters the band-offset is type-I whereas at experimentally relevant sizes the offset turns up to be of type-II. These findings highlight intriguing possibilities to modulate electron and hole separations as well as electronic and optical properties by simply modifying the crystal phase and the size of the junction.
Collapse
Affiliation(s)
| | | | | | - Maurizia Palummo
- Dipartimento di Fisica, Università di Roma Tor Vergata , Via della Ricerca Scientifica 1, 00133 Roma, Italy
- INFN, Laboratori Nazionali di Frascati, Via E. Fermi 40, I-00044 Frascati, Italy
| | - Riccardo Rurali
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra , 08193 Bellaterra, Barcelona, Spain
| |
Collapse
|