1
|
Li G, Zhang H, Han Y. Applications of Transmission Electron Microscopy in Phase Engineering of Nanomaterials. Chem Rev 2023; 123:10728-10749. [PMID: 37642645 DOI: 10.1021/acs.chemrev.3c00364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Phase engineering of nanomaterials (PEN) is an emerging field that aims to tailor the physicochemical properties of nanomaterials by precisely manipulating their crystal phases. To advance PEN effectively, it is vital to possess the capability of characterizing the structures and compositions of nanomaterials with precision. Transmission electron microscopy (TEM) is a versatile tool that combines reciprocal-space diffraction, real-space imaging, and spectroscopic techniques, allowing for comprehensive characterization with exceptional resolution in the domains of time, space, momentum, and, increasingly, even energy. In this Review, we first introduce the fundamental mechanisms behind various TEM-related techniques, along with their respective application scopes and limitations. Subsequently, we review notable applications of TEM in PEN research, including applications in fields such as metallic nanostructures, carbon allotropes, low-dimensional materials, and nanoporous materials. Specifically, we underscore its efficacy in phase identification, composition and chemical state analysis, in situ observations of phase evolution, as well as the challenges encountered when dealing with beam-sensitive materials. Furthermore, we discuss the potential generation of artifacts during TEM imaging, particularly in scanning modes, and propose methods to minimize their occurrence. Finally, we offer our insights into the present state and future trends of this field, discussing emerging technologies including four-dimensional scanning TEM, three-dimensional atomic-resolution imaging, and electron microscopy automation while highlighting the significance and feasibility of these advancements.
Collapse
Affiliation(s)
- Guanxing Li
- Advanced Membranes and Porous Materials Center, Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Hui Zhang
- Electron Microscopy Center, South China University of Technology, Guangzhou 510640, China
- School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Yu Han
- Advanced Membranes and Porous Materials Center, Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- Electron Microscopy Center, South China University of Technology, Guangzhou 510640, China
- School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| |
Collapse
|
2
|
Lozano MS, Gómez VJ. Epitaxial growth of crystal phase quantum dots in III-V semiconductor nanowires. NANOSCALE ADVANCES 2023; 5:1890-1909. [PMID: 36998660 PMCID: PMC10044505 DOI: 10.1039/d2na00956k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 03/06/2023] [Indexed: 06/19/2023]
Abstract
Crystal phase quantum dots (QDs) are formed during the axial growth of III-V semiconductor nanowires (NWs) by stacking different crystal phases of the same material. In III-V semiconductor NWs, both zinc blende (ZB) and wurtzite (WZ) crystal phases can coexist. The band structure difference between both crystal phases can lead to quantum confinement. Thanks to the precise control in III-V semiconductor NW growth conditions and the deep knowledge on the epitaxial growth mechanisms, it is nowadays possible to control, down to the atomic level, the switching between crystal phases in NWs forming the so-called crystal phase NW-based QDs (NWQDs). The shape and size of the NW bridge the gap between QDs and the macroscopic world. This review is focused on crystal phase NWQDs based on III-V NWs obtained by the bottom-up vapor-liquid-solid (VLS) method and their optical and electronic properties. Crystal phase switching can be achieved in the axial direction. In contrast, in the core/shell growth, the difference in surface energies between different polytypes can enable selective shell growth. One reason for the very intense research in this field is motivated by their excellent optical and electronic properties both appealing for applications in nanophotonics and quantum technologies.
Collapse
Affiliation(s)
- Miguel Sinusia Lozano
- Nanophotonics Technology Center, Universitat Politècnica de València, Camino de Vera s/n Building 8F, 2a Floor 46022 Valencia Spain
| | - Víctor J Gómez
- Nanophotonics Technology Center, Universitat Politècnica de València, Camino de Vera s/n Building 8F, 2a Floor 46022 Valencia Spain
| |
Collapse
|
3
|
Kuznetsov A, Roy P, Grudinin DV, Kondratev VM, Kadinskaya SA, Vorobyev AA, Kotlyar KP, Ubyivovk EV, Fedorov VV, Cirlin GE, Mukhin IS, Arsenin AV, Volkov VS, Bolshakov AD. Self-assembled photonic structure: a Ga optical antenna on GaP nanowires. NANOSCALE 2023; 15:2332-2339. [PMID: 36637064 DOI: 10.1039/d2nr04571k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Semiconductor nanowires are the perfect platform for nanophotonic applications owing to their resonant, waveguiding optical properties and technological capabilities providing control over their crystalline and chemical compositions. The vapor-liquid-solid growth mechanism allows the formation of hybrid metal-dielectric nanostructures promoting sub-wavelength light manipulation. In this work, we explore both experimentally and numerically the plasmonic effects promoted by a gallium (Ga) nanoparticle optical antenna decorating the facet of gallium phosphide (GaP) nanowires. Raman, photoluminescence and near-field mapping techniques are used to study the effects. We demonstrate several phenomena including field enhancement, antenna effect and increase in internal reflection. We show that the observed effects have to be considered when nanowires with a plasmonic particle are used in nanophotonic circuits and discuss the ways for utilization of these effects for efficient coupling of light into nanowire waveguide and field tailoring. The results open up promising pathways for the development of both passive and active nanophotonic elements, light harvesting and sensorics.
Collapse
Affiliation(s)
- Alexey Kuznetsov
- St Petersburg State University, St Petersburg 199034, Russia.
- Center for nanotechnologies, Alferov University, Saint Petersburg 194021, Russia
| | - Prithu Roy
- ITMO University, 197101, Saint Petersburg, Russia
| | - Dmitry V Grudinin
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Valeriy M Kondratev
- Center for nanotechnologies, Alferov University, Saint Petersburg 194021, Russia
| | | | - Alexandr A Vorobyev
- Center for nanotechnologies, Alferov University, Saint Petersburg 194021, Russia
| | - Konstantin P Kotlyar
- St Petersburg State University, St Petersburg 199034, Russia.
- Center for nanotechnologies, Alferov University, Saint Petersburg 194021, Russia
| | | | - Vladimir V Fedorov
- Center for nanotechnologies, Alferov University, Saint Petersburg 194021, Russia
| | - George E Cirlin
- St Petersburg State University, St Petersburg 199034, Russia.
| | - Ivan S Mukhin
- Center for nanotechnologies, Alferov University, Saint Petersburg 194021, Russia
- ITMO University, 197101, Saint Petersburg, Russia
- Higher School of Engineering Physics, Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg 195251, Russia
| | - Aleksey V Arsenin
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Valentyn S Volkov
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Alexey D Bolshakov
- St Petersburg State University, St Petersburg 199034, Russia.
- Center for nanotechnologies, Alferov University, Saint Petersburg 194021, Russia
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| |
Collapse
|
4
|
Arif O, Zannier V, Rossi F, De Matteis D, Kress K, De Luca M, Zardo I, Sorba L. GaAs/GaP superlattice nanowires: growth, vibrational and optical properties. NANOSCALE 2023; 15:1145-1153. [PMID: 35903972 PMCID: PMC9851173 DOI: 10.1039/d2nr02350d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/18/2022] [Indexed: 06/15/2023]
Abstract
Nanowire geometry allows semiconductor heterostructures to be obtained that are not achievable in planar systems, as in, for example, axial superlattices made of large lattice mismatched materials. This provides a great opportunity to explore new optical transitions and vibrational properties resulting from the superstructure. Moreover, superlattice nanowires are expected to show improved thermoelectric properties, owing to the dominant role of surfaces and interfaces that can scatter phonons more effectively, reducing the lattice thermal conductivity. Here, we show the growth of long (up to 100 repetitions) GaAs/GaP superlattice nanowires with different periodicities, uniform layer thicknesses, and sharp interfaces, realized by means of Au-assisted chemical beam epitaxy. By optimizing the growth conditions, we obtained great control of the nanowire diameter, growth rate, and superlattice periodicity, offering a valuable degree of freedom for engineering photonic and phononic properties at the nanoscale. As a proof of concept, we analyzed a single type of superlattice nanowire with a well-defined periodicity and we observed room temperature optical emission and new phonon modes. Our results prove that high-quality GaAs/GaP superlattice nanowires have great potential for phononic and optoelectronic studies and applications.
Collapse
Affiliation(s)
- Omer Arif
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, I-56127 Pisa, Italy.
| | - Valentina Zannier
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, I-56127 Pisa, Italy.
| | - Francesca Rossi
- IMEM-CNR, Parco Area delle Scienze 37/A, I-43124 Parma, Italy
| | - Diego De Matteis
- Physics Department, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Katharina Kress
- Physics Department, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Marta De Luca
- Physics Department, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
- Physics Department, Sapienza University of Rome, P.le Aldo Moro 2, 00185 Rome, Italy
| | - Ilaria Zardo
- Physics Department, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Lucia Sorba
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, I-56127 Pisa, Italy.
| |
Collapse
|
5
|
Li A, Hauge HIT, Verheijen MA, Bakkers EPAM, Tucker RT, Vincent L, Renard C. Hexagonal silicon-germanium nanowire branches with tunable composition. NANOTECHNOLOGY 2022; 34:015601. [PMID: 36126589 DOI: 10.1088/1361-6528/ac9317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 09/20/2022] [Indexed: 06/15/2023]
Abstract
Hexagonal SiGe-2H has been recently shown to have a direct bandgap, and holds the promise to be compatible with silicon technology. Hexagonal Si and Ge have been grown on an epitaxial lattice matched template consisting of wurtzite GaP and GaAs, respectively. Here, we present the growth of hexagonal Si and SiGe nanowire branches grown from a wurtzite stem by the vapor-liquid-solid growth mode, which is substantiated byin situtransmission electron microscopy. We show that the composition can be tuned through the whole range of stoichiometry from Si to Ge, and the possibility to realize Si and SiGe heterostructures in these branches.
Collapse
Affiliation(s)
- A Li
- Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - H I T Hauge
- Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - M A Verheijen
- Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- Eurofins Materials Science, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands
| | - E P A M Bakkers
- Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - R T Tucker
- Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- Department of Electrical & Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4, Canada
| | - L Vincent
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, F-91120, Palaiseau, France
| | - C Renard
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, F-91120, Palaiseau, France
| |
Collapse
|
6
|
Mårtensson EK, Johansson J, Dick KA. Simulating Vapor–Liquid–Solid Growth of Au-Seeded InGaAs Nanowires. ACS NANOSCIENCE AU 2022; 2:239-249. [PMID: 37101824 PMCID: PMC10125151 DOI: 10.1021/acsnanoscienceau.1c00052] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ternary III-V nanowires are commonly grown using the Au-seeded vapor-liquid-solid method, wherein the solid nanowires are grown from nanoscale liquid seed particles, which are supplied with growth species from the surrounding vapor phase. A result of the small size of these seed particles is that their composition can vary significantly during the cyclical layer-by-layer growth, despite experiencing a constant pressure of growth species from the surrounding vapor phase. Variations in the seed particle composition can greatly affect the solid nanowire composition, and these cyclical dynamics are poorly understood for ternary nanowire growth. Here, we present a method for simulating nanowire growth which captures the complex cyclical dynamics using a kinetic Monte Carlo framework. In the framework, a nanowire grows through the attachment or detachment of one III-V pair at the time, with rates that are based on the momentary composition of the seed particle. The composition of the seed evolves through the attachment and detachment of III-V pairs to the solid nanowire and through the impingement or evaporation of single atoms to the surrounding vapor. Here, we implement this framework using the As-Au-Ga-In materials system and use it to simulate the growth of Au-seeded InGaAs nanowires with an average solid Ga/III ratio around 0.5. The results show that nucleation preferentially occurs via clusters of InAs and that the compositional hierarchy of the liquid seed (X As < X Ga < X In) determines much of the dynamics of the system. We see that imposing a constraint on the simulation, that only the most recently attached III-V pair can be detached, resulted in a significant narrowing of the compositional profile of the nanowire. In addition, our results suggest that, for ternary systems where the two binaries are heavily mismatched, the dynamics of the seed particle may result in an oscillating compositional profile.
Collapse
Affiliation(s)
- Erik K. Mårtensson
- NanoLund and Division of Solid State Physics, Lund University, SE-221 00 Lund, Sweden
| | - Jonas Johansson
- NanoLund and Division of Solid State Physics, Lund University, SE-221 00 Lund, Sweden
| | - Kimberly A. Dick
- NanoLund and Division of Solid State Physics, Lund University, SE-221 00 Lund, Sweden
- Centre for Analysis and Synthesis, Lund University, SE-221 00 Lund, Sweden
| |
Collapse
|
7
|
Tornberg M, Sjökvist R, Kumar K, Andersen CR, Maliakkal CB, Jacobsson D, Dick KA. Direct Observations of Twin Formation Dynamics in Binary Semiconductors. ACS NANOSCIENCE AU 2022; 2:49-56. [PMID: 37101516 PMCID: PMC10125175 DOI: 10.1021/acsnanoscienceau.1c00021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
With the increased demand for controlled deterministic growth of III-V semiconductors at the nanoscale, the impact and interest of understanding defect formation and crystal structure switching becomes increasingly important. Vapor-liquid-solid (VLS) growth of semiconductor nanocrystals is an important mechanism for controlling and studying the formation of individual crystal layers and stacking defects. Using in situ studies, combining atomic resolution of transmission electron microscopy and controlled VLS crystal growth using metal organic chemical vapor deposition, we investigate the simplest achievable change in atomic layer stacking-single twinned layers formed in GaAs. Using Au-assisted GaAs nanowires of various diameters, we study the formation of individual layers with atomic resolution to reveal the growth difference in forming a twin defect. We determine that the formation of a twinned layer occurs significantly more slowly than that of a normal crystal layer. To understand this, we conduct thermodynamic modeling and determine that the propagation of a twin is limited by the energy cost of forming the twin interface. Finally, we determine that the slower propagation of twinned layers increases the probability of additional layers nucleating, such that multiple layers grow simultaneously. This observation challenges the current understanding that continuous uniform epitaxial growth, especially in the case of liquid-metal assisted nanowires, proceeds one single layer at a time and that its progression is limited by the nucleation rate.
Collapse
Affiliation(s)
- Marcus Tornberg
- Centre
for Analysis and Synthesis, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
| | - Robin Sjökvist
- Centre
for Analysis and Synthesis, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
| | - Krishna Kumar
- Centre
for Analysis and Synthesis, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
| | - Christopher R. Andersen
- Centre
for Analysis and Synthesis, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
- National
Centre for Nano Fabrication and Characterization, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Carina B. Maliakkal
- Centre
for Analysis and Synthesis, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
| | - Daniel Jacobsson
- Centre
for Analysis and Synthesis, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
- National
Center for High Resolution Electron Microscopy (nCHREM), Lund University, 22100 Lund, Sweden
| | - Kimberly A. Dick
- Centre
for Analysis and Synthesis, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
- National
Center for High Resolution Electron Microscopy (nCHREM), Lund University, 22100 Lund, Sweden
| |
Collapse
|
8
|
Fedorov VV, Dvoretckaia LN, Kirilenko DA, Mukhin IS, Dubrovskii VG. Formation of wurtzite sections in self-catalyzed GaP nanowires by droplet consumption. NANOTECHNOLOGY 2021; 32:495601. [PMID: 34433149 DOI: 10.1088/1361-6528/ac20fe] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 08/25/2021] [Indexed: 06/13/2023]
Abstract
Wurtzite GaP nanowires are interesting for the direct bandgap engineering and can be used as templates for further growth of hexagonal Si shells. Most wurtzite GaP nanowires have previously been obtained with Au catalysts. Here, we show that long (∼500 nm) wurtzite sections are formed in the top parts of self-catalyzed GaP nanowires grown by molecular beam epitaxy on Si(111) substrates in the droplet consumption stage, which is achieved by abruptly increasing the atomic V/III flux ratio from 2 to 3. We investigate the temperature dependence of the length of wurtzite sections and show that the longest sections are obtained at 610 °C. A supporting model explains the observed trends using a phase diagram of GaP nanowires, where the wurtzite phase is formed within a certain range of the droplet contact angles. The optimal growth temperature for growing wurtzite nanowires corresponds to the largest diffusion length of Ga adatoms, which helps to maintain the required contact angle for the longest time.
Collapse
Affiliation(s)
- V V Fedorov
- Nanotechnology Research and Education Centre of the Russian Academy of Sciences, Alferov University, Khlopina 8/3, 194021 St. Petersburg, Russia
- Institute of Physics, Nanotechnology and Telecommunications, Peter the Great St. Petersburg Polytechnic University, Politekhnicheskaya 29, 195251 St. Petersburg, Russia
| | - L N Dvoretckaia
- Nanotechnology Research and Education Centre of the Russian Academy of Sciences, Alferov University, Khlopina 8/3, 194021 St. Petersburg, Russia
| | - D A Kirilenko
- Ioffe Institute, Politekhnicheskaya 26, 194021 St. Petersburg, Russia
| | - I S Mukhin
- Nanotechnology Research and Education Centre of the Russian Academy of Sciences, Alferov University, Khlopina 8/3, 194021 St. Petersburg, Russia
- School of Photonics, ITMO University, Kronverksky Prospekt 49, 197101 St. Petersburg, Russia
| | - V G Dubrovskii
- Faculty of Physics, St. Petersburg State University, Universitetskaya Emb. 13B, 199034, St. Petersburg, Russia
| |
Collapse
|
9
|
Tailoring Morphology and Vertical Yield of Self-Catalyzed GaP Nanowires on Template-Free Si Substrates. NANOMATERIALS 2021; 11:nano11081949. [PMID: 34443778 PMCID: PMC8400893 DOI: 10.3390/nano11081949] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/14/2021] [Accepted: 07/26/2021] [Indexed: 12/16/2022]
Abstract
Tailorable synthesis of III-V semiconductor heterostructures in nanowires (NWs) enables new approaches with respect to designing photonic and electronic devices at the nanoscale. We present a comprehensive study of highly controllable self-catalyzed growth of gallium phosphide (GaP) NWs on template-free silicon (111) substrates by molecular beam epitaxy. We report the approach to form the silicon oxide layer, which reproducibly provides a high yield of vertical GaP NWs and control over the NW surface density without a pre-patterned growth mask. Above that, we present the strategy for controlling both GaP NW length and diameter independently in single- or two-staged self-catalyzed growth. The proposed approach can be extended to other III-V NWs.
Collapse
|
10
|
De Luca M, Fasolato C, Verheijen MA, Ren Y, Swinkels MY, Kölling S, Bakkers EPAM, Rurali R, Cartoixà X, Zardo I. Phonon Engineering in Twinning Superlattice Nanowires. NANO LETTERS 2019; 19:4702-4711. [PMID: 31203630 PMCID: PMC6628185 DOI: 10.1021/acs.nanolett.9b01775] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/14/2019] [Indexed: 06/01/2023]
Abstract
One of the current challenges in nanoscience is tailoring the phononic properties of a material. This has long been a rather elusive task because several phonons have wavelengths in the nanometer range. Thus, high quality nanostructuring at that length-scale, unavailable until recently, is necessary for engineering the phonon spectrum. Here we report on the continuous tuning of the phononic properties of a twinning superlattice GaP nanowire by controlling its periodicity. Our experimental results, based on Raman spectroscopy and rationalized by means of ab initio theoretical calculations, give insight into the relation between local crystal structure, overall lattice symmetry, and vibrational properties, demonstrating how material engineering at the nanoscale can be successfully employed in the rational design of the phonon spectrum of a material.
Collapse
Affiliation(s)
- Marta De Luca
- Departement
Physik, Universität Basel, 4056 Basel, Switzerland
| | - Claudia Fasolato
- Departement
Physik, Universität Basel, 4056 Basel, Switzerland
- Dipartimento
di Fisica e Geologia, Università
degli Studi di Perugia, 06123 Perugia, Italy
| | - Marcel A. Verheijen
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | - Yizhen Ren
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | | | - Sebastian Kölling
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | - Erik P. A. M. Bakkers
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | - Riccardo Rurali
- Institut
de Ciència de Materials de Barcelona (ICMAB−CSIC), Campus de Bellaterra, 08193 Bellaterra, Barcelona, Spain
| | - Xavier Cartoixà
- Departament
d’Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Ilaria Zardo
- Departement
Physik, Universität Basel, 4056 Basel, Switzerland
| |
Collapse
|
11
|
Zamani RR, Arbiol J. Understanding semiconductor nanostructures via advanced electron microscopy and spectroscopy. NANOTECHNOLOGY 2019; 30:262001. [PMID: 30812017 DOI: 10.1088/1361-6528/ab0b0a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Transmission electron microscopy (TEM) offers an ample range of complementary techniques which are able to provide essential information about the physical, chemical and structural properties of materials at the atomic scale, and hence makes a vast impact on our understanding of materials science, especially in the field of semiconductor one-dimensional (1D) nanostructures. Recent advancements in TEM instrumentation, in particular aberration correction and monochromation, have enabled pioneering experiments in complex nanostructure material systems. This review aims to address these understandings through the applications of the methodology for semiconductor nanostructures. It points out various electron microscopy techniques, in particular scanning TEM (STEM) imaging and spectroscopy techniques, with their already-employed or potential applications on 1D nanostructured semiconductors. We keep the main focus of the paper on the electronic and optoelectronic properties of such semiconductors, and avoid expanding it further. In the first part of the review, we give a brief introduction to each of the STEM-based techniques, without detailed elaboration, and mention the recent technological and conceptual developments which lead to novel characterization methodologies. For further reading, we refer the audience to a handful of papers in the literature. In the second part, we highlight the recent examples of application of the STEM methodology on the 1D nanostructure semiconductor materials, especially III-V, II-V, and group IV bare and heterostructure systems. The aim is to address the research questions on various physical properties and introduce solutions by choosing the appropriate technique that can answer the questions. Potential applications will also be discussed, the ones that have already been used for bulk and 2D materials, and have shown great potential and promise for 1D nanostructure semiconductors.
Collapse
Affiliation(s)
- Reza R Zamani
- Department of Physics, Chalmers University of Technology, Gothenburg, SE-41296, Sweden. Interdisciplinary Centre for Electron Microscopy (CIME), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | | |
Collapse
|
12
|
Tornberg M, Jacobsson D, Persson AR, Wallenberg R, Dick KA, Kodambaka S. Kinetics of Au-Ga Droplet Mediated Decomposition of GaAs Nanowires. NANO LETTERS 2019; 19:3498-3504. [PMID: 31039317 DOI: 10.1021/acs.nanolett.9b00321] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Particle-assisted III-V semiconductor nanowire growth and applications thereof have been studied extensively. However, the stability of nanowires in contact with the particle and the particle chemical composition as a function of temperature remain largely unknown. In this work, we use in situ transmission electron microscopy to investigate the interface between a Au-Ga particle and the top facet of an ⟨1̅1̅1̅⟩-oriented GaAs nanowire grown via the vapor-liquid-solid process. We observed a thermally activated bilayer-by-bilayer removal of the GaAs facet in contact with the liquid particle during annealing between 300 and 420 °C in vacuum. Interestingly, the GaAs-removal rates initially depend on the thermal history of the sample and are time-invariant at later times. In situ X-ray energy dispersive spectroscopy was also used to determine that the Ga content in the particle at any given temperature remains constant over extended periods of time and increases with increasing temperature from 300 to 400 °C. We attribute the observed phenomena to droplet-assisted decomposition of GaAs at a rate that is controlled by the amount of Ga in the droplet. We suggest that the observed transients in removal rates are a direct consequence of time-dependent changes in the Ga content. Our results provide new insights into the role of droplet composition on the thermal stability of GaAs nanowires and complement the existing knowledge on the factors influencing nanowire growth. Moreover, understanding the nanowire stability and decomposition is important for improving processing protocols for the successful fabrication and sustained operation of nanowire-based devices.
Collapse
Affiliation(s)
- Marcus Tornberg
- Solid State Physics , Lund University , Box 118, 22100 Lund , Sweden
| | | | | | | | - Kimberly A Dick
- Solid State Physics , Lund University , Box 118, 22100 Lund , Sweden
| | - Suneel Kodambaka
- Department of Materials Science and Engineering , University of California Los Angeles , 410 Westwood Plaza , Los Angeles , California 90095 , United States
| |
Collapse
|
13
|
Dalacu D, Poole PJ, Williams RL. Nanowire-based sources of non-classical light. NANOTECHNOLOGY 2019; 30:232001. [PMID: 30703755 DOI: 10.1088/1361-6528/ab0393] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Sources of quantum light that utilize photonic nanowire designs have emerged as potential candidates for high efficiency non-classical light generation in quantum information processing. In this review we cover the different platforms used to produce nanowire-based sources, highlighting the importance of waveguide design and material properties in achieving optimal performance. The limitations of the sources are identified and routes to optimization are proposed. State-of-the-art nanowire sources are compared to other solid-state quantum emitter platforms with regard to the key metrics of single photon purity, indistinguishability and entangled-pair fidelity to maximally entangled Bell states. We also discuss the unique ability of the nanowire platform to incorporate multiple emitters in the same optical mode and consider potential applications. Finally, routes to on-chip integration are discussed and the challenges facing the development of a nanowire-based scalable architecture are presented.
Collapse
Affiliation(s)
- Dan Dalacu
- National Research Council of Canada, Ottawa, Ontario, K1A 0R6, Canada
| | | | | |
Collapse
|
14
|
Güniat L, Caroff P, Fontcuberta I Morral A. Vapor Phase Growth of Semiconductor Nanowires: Key Developments and Open Questions. Chem Rev 2019; 119:8958-8971. [PMID: 30998006 DOI: 10.1021/acs.chemrev.8b00649] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nanowires are filamentary crystals with a tailored diameter that can be obtained using a plethora of different synthesis techniques. In this review, we focus on the vapor phase, highlighting the most influential achievements along with a historical perspective. Starting with the discovery of VLS, we feature the variety of structures and materials that can be synthesized in the nanowire form. We then move on to establish distinct features such as the three-dimensional heterostructure/doping design and polytypism. We summarize the status quo of the growth mechanisms, recently confirmed by in situ electron microscopy experiments and defining common ground between the different synthesis techniques. We then propose a selection of remaining defects, starting from what we know and going toward what is still to be learned. We believe this review will serve as a reference for neophytes but also as an insight for experts in an effort to bring open questions under a new light.
Collapse
Affiliation(s)
- Lucas Güniat
- Laboratory of Semiconductor Materials, Institute of Materials , École Polytechnique Fédérale de Lausanne , 1015 Lausanne , Switzerland
| | - Philippe Caroff
- Microsoft Quantum Lab Delft , Delft University of Technology , 2600 GA Delft , The Netherlands
| | - Anna Fontcuberta I Morral
- Laboratory of Semiconductor Materials, Institute of Materials , École Polytechnique Fédérale de Lausanne , 1015 Lausanne , Switzerland.,Institute of Physics , École Polytechnique Fédérale de Lausanne , 1015 Lausanne , Switzerland
| |
Collapse
|
15
|
Lehmann S, Wallentin J, Mårtensson EK, Ek M, Deppert K, Dick KA, Borgström MT. Simultaneous Growth of Pure Wurtzite and Zinc Blende Nanowires. NANO LETTERS 2019; 19:2723-2730. [PMID: 30888174 DOI: 10.1021/acs.nanolett.9b01007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The opportunity to engineer III-V nanowires in wurtzite and zinc blende crystal structure allows for exploring properties not conventionally available in the bulk form as well as opening the opportunity for use of additional degrees of freedom in device fabrication. However, the fundamental understanding of the nature of polytypism in III-V nanowire growth is still lacking key ingredients to be able to connect the results of modeling and experiments. Here we show InP nanowires of both pure wurtzite and pure zinc blende grown simultaneously on the same InP [100]-oriented substrate. We find wurtzite nanowires to grow along [Formula: see text] and zinc blende counterparts along [Formula: see text]. Further, we discuss the nucleation, growth, and polytypism of our nanowires against the background of existing theory. Our results demonstrate, first, that the crystal growth conditions for wurtzite and zinc blende nanowire growth are not mutually exclusive and, second, that the interface energies predominantly determine the crystal structure of the nanowires.
Collapse
Affiliation(s)
- Sebastian Lehmann
- Solid State Physics and NanoLund , Lund University , Box 118, S-221 00 Lund , Sweden
| | - Jesper Wallentin
- Solid State Physics and NanoLund , Lund University , Box 118, S-221 00 Lund , Sweden
- Synchrotron Radiation Research and NanoLund , Box 118, S-221 00 Lund , Sweden
| | - Erik K Mårtensson
- Solid State Physics and NanoLund , Lund University , Box 118, S-221 00 Lund , Sweden
| | - Martin Ek
- Centre for Analysis and Synthesis , Lund University , Box 124, 221 00 , Lund , Sweden
| | - Knut Deppert
- Solid State Physics and NanoLund , Lund University , Box 118, S-221 00 Lund , Sweden
| | - Kimberly A Dick
- Solid State Physics and NanoLund , Lund University , Box 118, S-221 00 Lund , Sweden
- Centre for Analysis and Synthesis , Lund University , Box 124, 221 00 , Lund , Sweden
| | - Magnus T Borgström
- Solid State Physics and NanoLund , Lund University , Box 118, S-221 00 Lund , Sweden
| |
Collapse
|
16
|
Park K, Lee J, Kim D, Seo J, Kim J, Ahn JP, Park J. Synthesis of Polytypic Gallium Phosphide and Gallium Arsenide Nanowires and Their Application as Photodetectors. ACS OMEGA 2019; 4:3098-3104. [PMID: 31459529 PMCID: PMC6648578 DOI: 10.1021/acsomega.8b03548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 01/04/2019] [Indexed: 05/23/2023]
Abstract
One-dimensional semiconductor nanowires often contain polytypic structures, owing to the co-existence of different crystal phases. Therefore, understanding the properties of polytypic structures is of paramount importance for many promising applications in high-performance nanodevices. Herein, we synthesized nanowires of typical III-V semiconductors, namely, gallium phosphide and gallium arsenide by using the chemical vapor transport method. The growth directions ([111] and [211]) could be switched by changing the experimental conditions, such as H2 gas flow; thus, various polytypic structures were produced simultaneously in a controlled manner. The nanobeam electron diffraction technique was employed to obtain strain mapping of the nanowires by visualizing the polytypic structures along the [111] direction. Micro-Raman spectra for individual nanowires were collected, confirming the presence of wurtzite phase in the polytypic nanowires. Further, we fabricated the photodetectors using the single nanowires, and the polytypic structures are shown to decrease the photosensitivity. Our systematic analysis provides important insight into the polytypic structures of nanowires.
Collapse
Affiliation(s)
- Kidong Park
- Department
of Chemistry, Korea University, Sejong 339-700, Korea
| | - Jinha Lee
- Department
of Chemistry, Korea University, Sejong 339-700, Korea
| | - Doyeon Kim
- Department
of Chemistry, Korea University, Sejong 339-700, Korea
| | - Jaemin Seo
- Department
of Chemistry, Korea University, Sejong 339-700, Korea
| | - Jundong Kim
- Department
of Chemistry, Korea University, Sejong 339-700, Korea
| | - Jae-Pyoung Ahn
- Advanced
Analysis Center, Korea Institute of Science
and Technology, Seoul 136-791, Korea
| | - Jeunghee Park
- Department
of Chemistry, Korea University, Sejong 339-700, Korea
| |
Collapse
|
17
|
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
|
18
|
Fasolato C, De Luca M, Djomani D, Vincent L, Renard C, Di Iorio G, Paillard V, Amato M, Rurali R, Zardo I. Crystalline, Phononic, and Electronic Properties of Heterostructured Polytypic Ge Nanowires by Raman Spectroscopy. NANO LETTERS 2018; 18:7075-7084. [PMID: 30185053 DOI: 10.1021/acs.nanolett.8b03073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Semiconducting nanowires (NWs) offer the unprecedented opportunity to host different crystal phases in a nanostructure, which enables the formation of polytypic heterostructures where the material composition is unchanged. This characteristic boosts the potential of polytypic heterostructured NWs for optoelectronic and phononic applications. In this work, we investigate cubic Ge NWs where small (∼20 nm) hexagonal domains are formed due to a strain-induced phase transformation. By combining a nondestructive optical technique (Raman spectroscopy) with density-functional theory (DFT) calculations, we assess the phonon properties of hexagonal Ge, determine the crystal phase variations along the NW axis, and, quite remarkably, reconstruct the relative orientation of the two polytypes. Moreover, we provide information on the electronic band alignment of the heterostructure at points of the Brillouin zone different from the one (Γ) where the direct band gap recombination in hexagonal Ge takes place. We demonstrate the versatility of Raman spectroscopy and show that it can be used to determine the main crystalline, phononic, and electronic properties of the most challenging type of heterostructure (a polytypic, nanoscale heterostructure with constant material composition). The general procedure that we establish can be applied to several types of heterostructures.
Collapse
Affiliation(s)
- Claudia Fasolato
- Departement Physik , Universität Basel , Klingelbergstrasse 82 , 4056 Basel , Switzerland
| | - Marta De Luca
- Departement Physik , Universität Basel , Klingelbergstrasse 82 , 4056 Basel , Switzerland
| | - Doriane Djomani
- Centre de Nanosciences et Nanotechnologies (C2N), CNRS , Univ. Paris-Sud, Université Paris-Saclay , Bât 220, rue André Ampère, Centre scientifique d'Orsay , F91405 Orsay cedex, France
| | - Laetitia Vincent
- Centre de Nanosciences et Nanotechnologies (C2N), CNRS , Univ. Paris-Sud, Université Paris-Saclay , Bât 220, rue André Ampère, Centre scientifique d'Orsay , F91405 Orsay cedex, France
| | - Charles Renard
- Centre de Nanosciences et Nanotechnologies (C2N), CNRS , Univ. Paris-Sud, Université Paris-Saclay , Bât 220, rue André Ampère, Centre scientifique d'Orsay , F91405 Orsay cedex, France
| | - Giulia Di Iorio
- Departement Physik , Universität Basel , Klingelbergstrasse 82 , 4056 Basel , Switzerland
| | | | - Michele Amato
- Laboratoire de Physique des Solides (LPS), CNRS , Univ. Paris-Sud, Université Paris-Saclay, Centre scientifique d'Orsay , F-91405 Orsay cedex, France
| | - Riccardo Rurali
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) , Campus de Bellaterra , 08193 Bellaterra, Barcelona , Spain
| | - Ilaria Zardo
- Departement Physik , Universität Basel , Klingelbergstrasse 82 , 4056 Basel , Switzerland
| |
Collapse
|
19
|
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
|
20
|
Oliveira DS, Zavarize M, Tizei LHG, Walls M, Ospina CA, Iikawa F, Ugarte D, Cotta MA. Different growth regimes in InP nanowire growth mediated by Ag nanoparticles. NANOTECHNOLOGY 2017; 28:505604. [PMID: 29099391 DOI: 10.1088/1361-6528/aa9816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the existence of two different regimes in one-step Ag-seeded InP nanowire growth. The vapor-liquid-solid-mechanism is present at larger In precursor flows and temperatures, ∼500 °C, yielding high aspect ratio and pure wurtzite InP nanowires with a semi-spherical metal particle at the thin apex. Periodic diameter oscillations can be achieved under extreme In supersaturations at this temperature range, showing the presence of a liquid catalyst. However, under lower temperatures and In precursor flows, large diameter InP nanowires with mixed wurtzite/zincblende segments are obtained, similarly to In-assisted growth. Chemical composition analysis suggest that In-rich droplet formation is catalyzed at the substrate surface via Ag nanoparticles; this process might be facilitated by the sulfur contamination detected in these nanoparticles. Furthermore, part of the original Ag nanoparticle remains solid and is embedded inside the actual catalyst, providing an in situ method to switch growth mechanisms upon changing In precursor flow. Nevertheless, our Ag-seeded InP nanowires exhibit overall optical emission spectra consistent with the observed structural properties and similar to Au-catalyzed InP nanowires. We thus show that Ag nanoparticles may be a suitable replacement for Au in InP nanowire growth.
Collapse
Affiliation(s)
- D S Oliveira
- Gleb Wataghin Physics Institute, University of Campinas, 13083-859 Campinas, SP, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Halder NN, Kelrich A, Cohen S, Ritter D. Pure wurtzite GaP nanowires grown on zincblende GaP substrates by selective area vapor liquid solid epitaxy. NANOTECHNOLOGY 2017; 28:465603. [PMID: 28885983 DOI: 10.1088/1361-6528/aa8b60] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the growth of single phase wurtzite (WZ) GaP nanowires (NWs) on GaP (111) B substrates by metal organic molecular beam epitaxy following the selective area vapor-liquid-solid (SA-VLS) approach. During the SA-VLS process, precursors are supplied directly to the NW sidewalls, and the short diffusion length of gallium (or its precursors) does not significantly limit axial growth. Transmission electron microscopy (TEM) images reveal that no stacking faults are present along a 600 nm long NW. The lattice constants of the pure WZ GaP obtained from the TEM images agree with values determined previously by x-ray diffraction from non-pure NW ensembles.
Collapse
Affiliation(s)
- Nripendra N Halder
- Electrical Engineering Faculty, Technion Israel Institute of Technology, Haifa 32000, Israel
| | | | | | | |
Collapse
|
22
|
Knutsson JV, Lehmann S, Hjort M, Lundgren E, Dick KA, Timm R, Mikkelsen A. Electronic Structure Changes Due to Crystal Phase Switching at the Atomic Scale Limit. ACS NANO 2017; 11:10519-10528. [PMID: 28960985 DOI: 10.1021/acsnano.7b05873] [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
The perfect switching between crystal phases with different electronic structure in III-V nanowires allows for the design of superstructures with quantum wells only a single atomic layer wide. However, it has only been indirectly inferred how the electronic structure will vary down to the smallest possible crystal segments. We use low-temperature scanning tunneling microscopy and spectroscopy to directly probe the electronic structure of Zinc blende (Zb) segments in Wurtzite (Wz) InAs nanowires with atomic-scale precision. We find that the major features in the band structure change abruptly down to a single atomic layer level. Distinct Zb electronic structure signatures are observed on both the conduction and valence band sides for the smallest possible Zb segment: a single InAs bilayer. We find evidence of confined states in the region of both single and double bilayer Zb segments indicative of the formation of crystal segment quantum wells due to the smaller band gap of Zb as compared to Wz. In contrast to the internal electronic structure of the nanowire, surface states located in the band gap were found to be only weakly influenced by the presence of the smallest Zb segments. Our findings directly demonstrate the feasibility of crystal phase switching for the ultimate limit of atomistic band structure engineering of quantum confined structures. Further, it indicates that band gap values obtained for the bulk are reasonable to use even for the smallest crystal segments. However, we also find that the suppression of surface and interface states could be necessary in the use of this effect for engineering of future electronic devices.
Collapse
Affiliation(s)
| | - Sebastian Lehmann
- Department of Physics & NanoLund, Lund University , P.O. Box 118, 22 100 Lund, Sweden
| | - Martin Hjort
- Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States
| | - Edvin Lundgren
- Department of Physics & NanoLund, Lund University , P.O. Box 118, 22 100 Lund, Sweden
| | - Kimberly A Dick
- Department of Physics & NanoLund, Lund University , P.O. Box 118, 22 100 Lund, Sweden
- Center for Analysis and Synthesis, Lund University , P.O. Box 124, 221 00 Lund, Sweden
| | - Rainer Timm
- Department of Physics & NanoLund, Lund University , P.O. Box 118, 22 100 Lund, Sweden
| | - Anders Mikkelsen
- Department of Physics & NanoLund, Lund University , P.O. Box 118, 22 100 Lund, Sweden
| |
Collapse
|
23
|
Assali S, Lähnemann J, Vu TTT, Jöns KD, Gagliano L, Verheijen MA, Akopian N, Bakkers EPAM, Haverkort JEM. Crystal Phase Quantum Well Emission with Digital Control. NANO LETTERS 2017; 17:6062-6068. [PMID: 28892396 PMCID: PMC5642001 DOI: 10.1021/acs.nanolett.7b02489] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/06/2017] [Indexed: 05/31/2023]
Abstract
One of the major challenges in the growth of quantum well and quantum dot heterostructures is the realization of atomically sharp interfaces. Nanowires provide a new opportunity to engineer the band structure as they facilitate the controlled switching of the crystal structure between the zinc-blende (ZB) and wurtzite (WZ) phases. Such a crystal phase switching results in the formation of crystal phase quantum wells (CPQWs) and quantum dots (CPQDs). For GaP CPQWs, the inherent electric fields due to the discontinuity of the spontaneous polarization at the WZ/ZB junctions lead to the confinement of both types of charge carriers at the opposite interfaces of the WZ/ZB/WZ structure. This confinement leads to a novel type of transition across a ZB flat plate barrier. Here, we show digital tuning of the visible emission of WZ/ZB/WZ CPQWs in a GaP nanowire by changing the thickness of the ZB barrier. The energy spacing between the sharp emission lines is uniform and is defined by the addition of single ZB monolayers. The controlled growth of identical quantum wells with atomically flat interfaces at predefined positions featuring digitally tunable discrete emission energies may provide a new route to further advance entangled photons in solid state quantum systems.
Collapse
Affiliation(s)
- S. Assali
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
| | - J. Lähnemann
- Paul-Drude-Institut
für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - T. T. T. Vu
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
| | - K. D. Jöns
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA, Delft, The Netherlands
| | - L. Gagliano
- 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 Services Eindhoven, High Tech Campus 11, 5656 AE, Eindhoven, The
Netherlands
| | - N. Akopian
- 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
| | - 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
| | - J. E. M. Haverkort
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
| |
Collapse
|
24
|
Steidl M, Koppka C, Winterfeld L, Peh K, Galiana B, Supplie O, Kleinschmidt P, Runge E, Hannappel T. Impact of Rotational Twin Boundaries and Lattice Mismatch on III-V Nanowire Growth. ACS NANO 2017; 11:8679-8689. [PMID: 28881138 DOI: 10.1021/acsnano.7b01228] [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
Pseudomorphic planar III-V transition layers greatly facilitate the epitaxial integration of vapor-liquid-solid grown III-V nanowires (NW) on Si(111) substrates. Heteroepitaxial (111) layer growth, however, is commonly accompanied by the formation of rotational twins. We find that rotational twin boundaries (RTBs), which intersect the surface of GaP/Si(111) heterosubstrates, generally cause horizontal NW growth and may even suppress NW growth entirely. Away from RTBs, the NW growth direction switches from horizontal to vertical in the case of homoepitaxial GaP NWs, whereas heteroepitaxial GaAs NWs continue growing horizontally. To understand this rich phenomenology, we develop a model based on classical nucleation theory. Independent of the occurrence of RTBs and specific transition layers, our model can generally explain the prevalent observation of horizontal III-V NW growth in lattice mismatched systems and the high crystal quality of horizontal nanowires.
Collapse
Affiliation(s)
- Matthias Steidl
- Department of Photovoltaics, Institute of Physics and Institute of Micro- and Nanotechnologies , TU Ilmenau, 98693 Ilmenau, Germany
| | - Christian Koppka
- Department of Photovoltaics, Institute of Physics and Institute of Micro- and Nanotechnologies , TU Ilmenau, 98693 Ilmenau, Germany
| | - Lars Winterfeld
- Department of Theoretical Physics I, Institute of Physics and Institute of Micro- and Nanotechnologies , TU Ilmenau, 98693 Ilmenau, Germany
| | - Katharina Peh
- Department of Photovoltaics, Institute of Physics and Institute of Micro- and Nanotechnologies , TU Ilmenau, 98693 Ilmenau, Germany
| | - Beatriz Galiana
- Physics Department, Universidad Carlos III de Madrid , 28911 Madrid, Spain
| | - Oliver Supplie
- Department of Photovoltaics, Institute of Physics and Institute of Micro- and Nanotechnologies , TU Ilmenau, 98693 Ilmenau, Germany
| | - Peter Kleinschmidt
- Department of Photovoltaics, Institute of Physics and Institute of Micro- and Nanotechnologies , TU Ilmenau, 98693 Ilmenau, Germany
| | - Erich Runge
- Department of Theoretical Physics I, Institute of Physics and Institute of Micro- and Nanotechnologies , TU Ilmenau, 98693 Ilmenau, Germany
| | - Thomas Hannappel
- Department of Photovoltaics, Institute of Physics and Institute of Micro- and Nanotechnologies , TU Ilmenau, 98693 Ilmenau, Germany
| |
Collapse
|
25
|
Assali S, Dijkstra A, Li A, Koelling S, Verheijen MA, Gagliano L, von den Driesch N, Buca D, Koenraad PM, Haverkort JEM, Bakkers EPAM. Growth and Optical Properties of Direct Band Gap Ge/Ge 0.87Sn 0.13 Core/Shell Nanowire Arrays. NANO LETTERS 2017; 17:1538-1544. [PMID: 28165747 DOI: 10.1021/acs.nanolett.6b04627] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Group IV semiconductor optoelectronic devices are now possible by using strain-free direct band gap GeSn alloys grown on a Ge/Si virtual substrate with Sn contents above 9%. Here, we demonstrate the growth of Ge/GeSn core/shell nanowire arrays with Sn incorporation up to 13% and without the formation of Sn clusters. The nanowire geometry promotes strain relaxation in the Ge0.87Sn0.13 shell and limits the formation of structural defects. This results in room-temperature photoluminescence centered at 0.465 eV and enhanced absorption above 98%. Therefore, direct band gap GeSn grown in a nanowire geometry holds promise as a low-cost and high-efficiency material for photodetectors operating in the short-wave infrared and thermal imaging devices.
Collapse
Affiliation(s)
- S Assali
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - A Dijkstra
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - A Li
- 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
- Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology , Pingleyuan 100, Beijing 100024, P. R. China
| | - S Koelling
- 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 Gagliano
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - N von den Driesch
- Peter Gruenberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Juelich, 52428 Juelich, Germany
| | - D Buca
- Peter Gruenberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Juelich, 52428 Juelich, Germany
| | - P M Koenraad
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - 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
|
26
|
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
|
27
|
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
|
28
|
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
|
29
|
Electronic Structures of Free-Standing Nanowires made from Indirect Bandgap Semiconductor Gallium Phosphide. Sci Rep 2016; 6:28240. [PMID: 27307081 PMCID: PMC4910168 DOI: 10.1038/srep28240] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/31/2016] [Indexed: 11/28/2022] Open
Abstract
We present a theoretical study of the electronic structures of freestanding nanowires made from gallium phosphide (GaP)—a III-V semiconductor with an indirect bulk bandgap. We consider [001]-oriented GaP nanowires with square and rectangular cross sections, and [111]-oriented GaP nanowires with hexagonal cross sections. Based on tight binding models, both the band structures and wave functions of the nanowires are calculated. For the [001]-oriented GaP nanowires, the bands show anti-crossing structures, while the bands of the [111]-oriented nanowires display crossing structures. Two minima are observed in the conduction bands, while the maximum of the valence bands is always at the Γ-point. Using double group theory, we analyze the symmetry properties of the lowest conduction band states and highest valence band states of GaP nanowires with different sizes and directions. The band state wave functions of the lowest conduction bands and the highest valence bands of the nanowires are evaluated by spatial probability distributions. For practical use, we fit the confinement energies of the electrons and holes in the nanowires to obtain an empirical formula.
Collapse
|
30
|
Vainorius N, Lehmann S, Gustafsson A, Samuelson L, Dick KA, Pistol ME. Wurtzite GaAs Quantum Wires: One-Dimensional Subband Formation. NANO LETTERS 2016; 16:2774-2780. [PMID: 27004550 DOI: 10.1021/acs.nanolett.6b00482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
It is of contemporary interest to fabricate nanowires having quantum confinement and one-dimensional subband formation. This is due to a host of applications, for example, in optical devices, and in quantum optics. We have here fabricated and optically investigated narrow, down to 10 nm diameter, wurtzite GaAs nanowires which show strong quantum confinement and the formation of one-dimensional subbands. The fabrication was bottom up and in one step using the vapor-liquid-solid growth mechanism. Combining photoluminescence excitation spectroscopy with transmission electron microscopy on the same individual nanowires, we were able to extract the effective masses of the electrons in the two lowest conduction bands as well as the effective masses of the holes in the two highest valence bands. Our results, combined with earlier demonstrations of thin crystal phase nanodots in GaAs, set the stage for the fabrication of crystal phase quantum dots having full three-dimensional confinement.
Collapse
Affiliation(s)
- Neimantas Vainorius
- Solid State Physics and NanoLund, Lund University , P.O. Box 118, SE-221 00 Lund, Sweden
| | - Sebastian Lehmann
- Solid State Physics and NanoLund, Lund University , P.O. Box 118, SE-221 00 Lund, Sweden
| | | | - Lars Samuelson
- Solid State Physics and NanoLund, Lund University , P.O. Box 118, SE-221 00 Lund, Sweden
| | - Kimberly A Dick
- Solid State Physics and NanoLund, Lund University , P.O. Box 118, SE-221 00 Lund, Sweden
- Centre for Analysis and Synthesis, Lund University , P.O. Box 124, SE-221 00 Lund, Sweden
| | - Mats-Erik Pistol
- Solid State Physics and NanoLund, Lund University , P.O. Box 118, SE-221 00 Lund, Sweden
| |
Collapse
|
31
|
Bouwes Bavinck M, Jöns KD, Zieliński M, Patriarche G, Harmand JC, Akopian N, Zwiller V. Photon Cascade from a Single Crystal Phase Nanowire Quantum Dot. NANO LETTERS 2016; 16:1081-1085. [PMID: 26806321 DOI: 10.1021/acs.nanolett.5b04217] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report the first comprehensive experimental and theoretical study of the optical properties of single crystal phase quantum dots in InP nanowires. Crystal phase quantum dots are defined by a transition in the crystallographic lattice between zinc blende and wurtzite segments and therefore offer unprecedented potential to be controlled with atomic layer accuracy without random alloying. We show for the first time that crystal phase quantum dots are a source of pure single-photons and cascaded photon-pairs from type II transitions with excellent optical properties in terms of intensity and line width. We notice that the emission spectra consist often of two peaks close in energy, which we explain with a comprehensive theory showing that the symmetry of the system plays a crucial role for the hole levels forming hybridized orbitals. Our results state that crystal phase quantum dots have promising quantum optical properties for single photon application and quantum optics.
Collapse
Affiliation(s)
- Maaike Bouwes Bavinck
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
| | - Klaus D Jöns
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
| | | | - Gilles Patriarche
- Laboratoire de Photonique et de Nanostructures, CNRS , route de Nozay , 91460 Marcoussis, France
| | - Jean-Christophe Harmand
- Laboratoire de Photonique et de Nanostructures, CNRS , route de Nozay , 91460 Marcoussis, France
| | - Nika Akopian
- Department of Photonics Engineering, Technical University of Denmark , 2800 Kongens Lyngby, Denmark
| | - Val Zwiller
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
- Department of Applied Physics, KTH Royal Institute of Technology , SE-100 44, Stockholm, Sweden
| |
Collapse
|