1
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Schmiedeke P, Döblinger M, Meinhold-Heerlein MA, Doganlar C, Finley JJ, Koblmüller G. Sb-saturated high-temperature growth of extended, self-catalyzed GaAsSb nanowires on silicon with high quality. NANOTECHNOLOGY 2023; 35:055601. [PMID: 37879325 DOI: 10.1088/1361-6528/ad06ce] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/25/2023] [Indexed: 10/27/2023]
Abstract
Ternary GaAsSb nanowires (NW) are key materials for integrated high-speed photonic applications on silicon (Si), where homogeneous, high aspect-ratio dimensions and high-quality properties for controlled absorption, mode confinement and waveguiding are much desired. Here, we demonstrate a unique high-temperature (high-T >650 °C) molecular beam epitaxial (MBE) approach to realize self-catalyzed GaAsSb NWs site-selectively on Si with high aspect-ratio and non-tapered morphologies under antimony (Sb)-saturated conditions. While hitherto reported low-moderate temperature growth processes result in early growth termination and inhomogeneous morphologies, the non-tapered nature of NWs under high-T growth is independent of the supply rates of relevant growth species. Analysis of dedicated Ga-flux and growth time series, allows us to pinpoint the microscopic mechanisms responsible for the elimination of tapering, namely concurrent vapor-solid, step-flow growth along NW side-facets enabled by enhanced Ga diffusion under the high-T growth. Performing growth in an Sb-saturated regime, leads to high Sb-content in VLS-GaAsSb NW close to 30% that is independent of Ga-flux. This independence enables multi-step growth via sequentially increased Ga-flux to realize uniform and very long (>7μm) GaAsSb NWs. The excellent properties of these NWs are confirmed by a completely phase-pure, twin-free zincblende (ZB) crystal structure, a homogeneous Sb-content along the VLS-GaAsSb NW growth axis, along with remarkably narrow, single-peak low-temperature photoluminescence linewidth (<15 meV) at wavelengths of ∼1100-1200 nm.
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Affiliation(s)
- P Schmiedeke
- Walter Schottky Institute and Physics Department, TUM School of Natural Sciences, Technical University of Munich, Garching, Germany
| | - M Döblinger
- Department of Chemistry, Ludwig-Maximilians-University Munich, Munich, Germany
| | - M A Meinhold-Heerlein
- Walter Schottky Institute and Physics Department, TUM School of Natural Sciences, Technical University of Munich, Garching, Germany
| | - C Doganlar
- Walter Schottky Institute and Physics Department, TUM School of Natural Sciences, Technical University of Munich, Garching, Germany
| | - J J Finley
- Walter Schottky Institute and Physics Department, TUM School of Natural Sciences, Technical University of Munich, Garching, Germany
| | - G Koblmüller
- Walter Schottky Institute and Physics Department, TUM School of Natural Sciences, Technical University of Munich, Garching, Germany
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2
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Forrer N, Nigro A, Gadea G, Zardo I. Influence of Different Carrier Gases, Temperature, and Partial Pressure on Growth Dynamics of Ge and Si Nanowires. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2879. [PMID: 37947724 PMCID: PMC10650493 DOI: 10.3390/nano13212879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 10/23/2023] [Accepted: 10/29/2023] [Indexed: 11/12/2023]
Abstract
The broad and fascinating properties of nanowires and their synthesis have attracted great attention as building blocks for functional devices at the nanoscale. Silicon and germanium are highly interesting materials due to their compatibility with standard CMOS technology. Their combination provides optimal templates for quantum applications, for which nanowires need to be of high quality, with carefully designed dimensions, crystal phase, and orientation. In this work, we present a detailed study on the growth kinetics of silicon (length 0.1-1 μm, diameter 10-60 nm) and germanium (length 0.06-1 μm, diameter 10-500 nm) nanowires grown by chemical vapor deposition applying the vapour-liquid-solid growth method catalysed by gold. The effects of temperature, partial pressure of the precursor gas, and different carrier gases are analysed via scanning electron microscopy. Argon as carrier gas enhances the growth rate at higher temperatures (120 nm/min for Ar and 48 nm/min H2), while hydrogen enhances it at lower temperatures (35 nm/min for H2 and 22 nm/min for Ar) due to lower heat capacity. Both materials exhibit two growth regimes as a function of the temperature. The tapering rate is about ten times lower for silicon nanowires than for germanium ones. Finally, we identify the optimal conditions for nucleation in the nanowire growth process.
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Affiliation(s)
- Nicolas Forrer
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland; (N.F.); (A.N.); (G.G.)
| | - Arianna Nigro
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland; (N.F.); (A.N.); (G.G.)
| | - Gerard Gadea
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland; (N.F.); (A.N.); (G.G.)
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Ilaria Zardo
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland; (N.F.); (A.N.); (G.G.)
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
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3
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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.
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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.
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4
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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.
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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
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5
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Gómez VJ, Marnauza M, Dick KA, Lehmann S. Growth selectivity control of InAs shells on crystal phase engineered GaAs nanowires. NANOSCALE ADVANCES 2022; 4:3330-3341. [PMID: 36131713 PMCID: PMC9417278 DOI: 10.1039/d2na00109h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 03/23/2022] [Indexed: 06/15/2023]
Abstract
In this work we demonstrate a two-fold selectivity control of InAs shells grown on crystal phase and morphology engineered GaAs nanowire (NW) core templates. This selectivity occurs driven by differences in surface energies of the NW core facets. The occurrence of the different facets itself is controlled by either forming different crystal phases or additional tuning of the core NW morphology. First, in order to study the crystal phase selectivity, GaAs NW cores with an engineered crystal phase in the axial direction were employed. A crystal phase selective growth of InAs on GaAs was found for high growth rates and short growth times. Secondly, the facet-dependant selectivity of InAs growth was studied on crystal phase controlled GaAs cores which were additionally morphology-tuned by homoepitaxial overgrowth. Following this route, the original hexagonal cores with {110} sidewalls were converted into triangular truncated NWs with ridges and predominantly {112}B facets. By precisely tuning the growth parameters, the growth of InAs is promoted over the ridges and reduced over the {112}B facets with indications of also preserving the crystal phase selectivity. In all cases (different crystal phase and facet termination), selectivity is lost for extended growth times, thus, limiting the total thickness of the shell grown under selective conditions. To overcome this issue we propose a 2-step growth approach, combining a high growth rate step followed by a low growth rate step. The control over the thickness of the InAs shells while maintaining the selectivity is demonstrated by means of a detailed transmission electron microscopy analysis. This proposed 2-step growth approach enables new functionalities in 1-D structures formed by using bottom-up techniques, with a high degree of control over shell thickness and deposition selectivity.
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Affiliation(s)
- Víctor J Gómez
- Nanophotonics Technology Center, Universidad Politécnica de Valencia Camino de Vera, s/n Building 8F | 2a Floor 46022 Valencia Spain
- Solid State Physics and NanoLund, Lund University Box 118 S-221 00 Lund Sweden
| | - Mikelis Marnauza
- Centre for Analysis and Synthesis and NanoLund, Lund University Box 124 221 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 and NanoLund, Lund University Box 124 221 00 Lund Sweden
| | - Sebastian Lehmann
- Solid State Physics and NanoLund, Lund University Box 118 S-221 00 Lund Sweden
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6
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König D, Smith SC. Analytical description of nanowires III: regular cross sections for wurtzite structures. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2022; 78:665-677. [PMID: 35975832 PMCID: PMC9370209 DOI: 10.1107/s2052520622004954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Setting out from König & Smith [Acta Cryst. (2019), B75, 788-802; Acta Cryst. (2021), B77, 861], we present an analytic description of nominal wurtzite-structure nanowire (NWire) cross sections, focusing on the underlying geometric-crystallographic description and on the associated number theory. For NWires with diameter dWire[i], we predict the number of NWire atoms NWire[i], the bonds between these Nbnd[i] and NWire interface bonds NIF[i] for a slab of unit-cell length, along with basic geometric variables, such as the specific length of interface facets, as well as widths, heights and total area of the cross section. These areas, the ratios of internal bonds per NWire atom, of internal-to-interface bonds and of interface bonds per NWire atom present fundamental tools to interpret any spectroscopic data which depend on the diameter and cross section shape of NWires. Our work paves the way for a fourth publication which - in analogy to König & Smith [Acta Cryst. (2022). B78, 643-664] - will provide adaptive number series to allow for arbitrary morphing of nominal w-structure NWire cross sections treated herein.
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Affiliation(s)
- Dirk König
- Integrated Materials Design Lab (IMDL), Research School of Physics and Engineering, The Australian National University, ACT 2601, Australia
- Institute of Semiconductor Electronics (IHT), RWTH Aachen University, 52074 Aachen, Germany
- Integrated Materials Design Centre (IMDC), University of New South Wales, NSW 2052, Australia
| | - Sean C. Smith
- Integrated Materials Design Lab (IMDL), Research School of Physics and Engineering, The Australian National University, ACT 2601, Australia
- Department of Applied Mathematics, Research School of Physics and Engineering, The Australian National University, ACT 2601, Australia
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7
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Kimura S, Gamo H, Katsumi Y, Motohisa J, Tomioka K. InP nanowire light-emitting diodes with different pn-junction structures. NANOTECHNOLOGY 2022; 33:305204. [PMID: 35395650 DOI: 10.1088/1361-6528/ac659a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/08/2022] [Indexed: 06/14/2023]
Abstract
We report on the characterization of wurtzite (WZ) InP nanowire (NW) light-emitting diodes (LEDs) with different pn junctions (axial and radial). The series resistance tended to be smaller in the NW-LED using core-shell InP NWs with a radial pn junction than in the NW-LED using InP NWs with an axial pn junction, indicating that radial pn junctions are more suitable for current injection. The electroluminescence (EL) properties of both NW LEDs revealed that the EL had three peaks originating from the zinc-blende (ZB) phase, WZ phase, and ZB/WZ heterojunction. Transmission electron microscopy showed that the dominant EL in the radial pn junction originated from the ZB/WZ interface across the stacking faults.
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Affiliation(s)
- S Kimura
- Graduate School of Information Science and Technology and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, Japan
| | - H Gamo
- Graduate School of Information Science and Technology and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, Japan
| | - Y Katsumi
- Graduate School of Information Science and Technology and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, Japan
| | - J Motohisa
- Graduate School of Information Science and Technology and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, Japan
| | - K Tomioka
- Graduate School of Information Science and Technology and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, Japan
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8
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Fan L, Yang D, Li D. A Review on Metastable Silicon Allotropes. MATERIALS 2021; 14:ma14143964. [PMID: 34300884 PMCID: PMC8303612 DOI: 10.3390/ma14143964] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/08/2021] [Accepted: 07/12/2021] [Indexed: 01/25/2023]
Abstract
Diamond cubic silicon is widely used for electronic applications, integrated circuits, and photovoltaics, due to its high abundance, nontoxicity, and outstanding physicochemical properties. However, it is a semiconductor with an indirect band gap, depriving its further development. Fortunately, other polymorphs of silicon have been discovered successfully, and new functional allotropes are continuing to emerge, some of which are even stable in ambient conditions and could form the basis for the next revolution in electronics, stored energy, and optoelectronics. Such structures can lead to some excellent features, including a wide range of direct or quasi-direct band gaps allowed efficient for photoelectric conversion (examples include Si-III and Si-IV), as well as a smaller volume expansion as lithium-battery anode material (such as Si24, Si46, and Si136). This review aims to give a detailed overview of these exciting new properties and routes for the synthesis of novel Si allotropes. Lastly, the key problems and the developmental trends are put forward at the end of this article.
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Affiliation(s)
- Linlin Fan
- State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China; (L.F.); (D.Y.)
| | - Deren Yang
- State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China; (L.F.); (D.Y.)
| | - Dongsheng Li
- State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China; (L.F.); (D.Y.)
- Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027, China
- Correspondence: ; Tel.: +86-571-8795-3180
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9
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Fadaly ET, Marzegalli A, Ren Y, Sun L, Dijkstra A, de Matteis D, Scalise E, Sarikov A, De Luca M, Rurali R, Zardo I, Haverkort JEM, Botti S, Miglio L, Bakkers EPAM, Verheijen MA. Unveiling Planar Defects in Hexagonal Group IV Materials. NANO LETTERS 2021; 21:3619-3625. [PMID: 33843244 PMCID: PMC8155321 DOI: 10.1021/acs.nanolett.1c00683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/01/2021] [Indexed: 06/12/2023]
Abstract
Recently synthesized hexagonal group IV materials are a promising platform to realize efficient light emission that is closely integrated with electronics. A high crystal quality is essential to assess the intrinsic electronic and optical properties of these materials unaffected by structural defects. Here, we identify a previously unknown partial planar defect in materials with a type I3 basal stacking fault and investigate its structural and electronic properties. Electron microscopy and atomistic modeling are used to reconstruct and visualize this stacking fault and its terminating dislocations in the crystal. From band structure calculations coupled to photoluminescence measurements, we conclude that the I3 defect does not create states within the hex-Ge and hex-Si band gap. Therefore, the defect is not detrimental to the optoelectronic properties of the hex-SiGe materials family. Finally, highlighting the properties of this defect can be of great interest to the community of hex-III-Ns, where this defect is also present.
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Affiliation(s)
- Elham
M. T. Fadaly
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | - Anna Marzegalli
- Dipartimento
di Fisica, Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
- L-NESS
and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, 20125 Milano, Italy
| | - Yizhen Ren
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | - Lin Sun
- Institut
für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - Alain Dijkstra
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | - Diego de Matteis
- Departement
Physik, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Emilio Scalise
- L-NESS
and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, 20125 Milano, Italy
| | - Andrey Sarikov
- L-NESS
and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, 20125 Milano, Italy
- V.
Lashkarev
Institute of Semiconductor Physics, National
Academy of Sciences of Ukraine, 45 Nauki avenue, 03028 Kyiv, Ukraine
| | - Marta De Luca
- Departement
Physik, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Riccardo Rurali
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Bellaterra, Spain
| | - Ilaria Zardo
- Departement
Physik, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Jos E. M. Haverkort
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | - Silvana Botti
- Institut
für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - Leo Miglio
- L-NESS
and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, 20125 Milano, Italy
| | - Erik P. A. M. Bakkers
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
| | - Marcel A. Verheijen
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB Eindhoven, The Netherlands
- Eurofins
Materials Science Netherlands BV, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands
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10
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de Matteis D, De Luca M, Fadaly EMT, Verheijen MA, López-Suárez M, Rurali R, Bakkers EPAM, Zardo I. Probing Lattice Dynamics and Electronic Resonances in Hexagonal Ge and Si xGe 1-x Alloys in Nanowires by Raman Spectroscopy. ACS NANO 2020; 14:6845-6856. [PMID: 32392038 PMCID: PMC7315630 DOI: 10.1021/acsnano.0c00762] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/11/2020] [Indexed: 06/11/2023]
Abstract
Recent advances in nanowire synthesis have enabled the realization of crystal phases that in bulk are attainable only under extreme conditions, i.e., high temperature and/or high pressure. For group IV semiconductors this means access to hexagonal-phase SixGe1-x nanostructures (with a 2H type of symmetry), which are predicted to have a direct band gap for x up to 0.5-0.6 and would allow the realization of easily processable optoelectronic devices. Exploiting the quasi-perfect lattice matching between GaAs and Ge, we synthesized hexagonal-phase GaAs-Ge and GaAs-SixGe1-x core-shell nanowires with x up to 0.59. By combining position-, polarization-, and excitation wavelength-dependent μ-Raman spectroscopy studies with first-principles calculations, we explore the full lattice dynamics of these materials. In particular, by obtaining frequency-composition calibration curves for the phonon modes, investigating the dependence of the phononic modes on the position along the nanowire, and exploiting resonant Raman conditions to unveil the coupling between lattice vibrations and electronic transitions, we lay the grounds for a deep understanding of the phononic properties of 2H-SixGe1-x nanostructured alloys and of their relationship with crystal quality, chemical composition, and electronic band structure.
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Affiliation(s)
| | - Marta De Luca
- Departement
Physik, Universität Basel, 4056 Basel, Switzerland
| | - Elham M. T. Fadaly
- Department
of Applied Physics, Eindhoven University
of Technology, 5612AP Eindhoven, The Netherlands
| | - Marcel A. Verheijen
- Department
of Applied Physics, Eindhoven University
of Technology, 5612AP Eindhoven, The Netherlands
| | - Miquel López-Suárez
- 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
| | - Erik P. A. M. Bakkers
- Department
of Applied Physics, Eindhoven University
of Technology, 5612AP Eindhoven, The Netherlands
| | - Ilaria Zardo
- Departement
Physik, Universität Basel, 4056 Basel, Switzerland
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11
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Fonseka HA, Caroff P, Guo Y, Sanchez AM, Tan HH, Jagadish C. Engineering the Side Facets of Vertical [100] Oriented InP Nanowires for Novel Radial Heterostructures. NANOSCALE RESEARCH LETTERS 2019; 14:399. [PMID: 31889237 PMCID: PMC6937364 DOI: 10.1186/s11671-019-3177-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/03/2019] [Indexed: 06/10/2023]
Abstract
In addition to being grown on industry-standard orientation, vertical [100] oriented nanowires present novel families of facets and related cross-sectional shapes. These nanowires are engineered to achieve a number of facet combinations and cross-sectional shapes, by varying their growth parameters within ranges that facilitate vertical growth. In situ post-growth annealing technique is used to realise other combinations that are unattainable solely using growth parameters. Two examples of possible novel radial heterostructures grown on these vertical [100] oriented nanowire facets are presented, demonstrating their potential in future applications.
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Affiliation(s)
- H. Aruni Fonseka
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601 Australia
- Department of Physics, University of Warwick, Coventry, CV4 7AL UK
| | - Philippe Caroff
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601 Australia
- Current Address: Microsoft Station Q, Delft University of Technology, 2600 GA Delft, Netherlands
| | - Yanan Guo
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601 Australia
- Current Address: Samsung Austin Semiconductors, 12100 Samsung Blvd, Austin, TX 78754 USA
| | - Ana M. Sanchez
- Department of Physics, University of Warwick, Coventry, CV4 7AL UK
| | - Hark Hoe Tan
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601 Australia
| | - Chennupati Jagadish
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601 Australia
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12
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Greenberg Y, Kelrich A, Cohen S, Kar-Narayan S, Ritter D, Calahorra Y. Strain-Mediated Bending of InP Nanowires through the Growth of an Asymmetric InAs Shell. NANOMATERIALS 2019; 9:nano9091327. [PMID: 31527424 PMCID: PMC6781057 DOI: 10.3390/nano9091327] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/12/2019] [Accepted: 09/13/2019] [Indexed: 11/16/2022]
Abstract
Controlling nanomaterial shape beyond its basic dimensionality is a concurrent challenge tackled by several growth and processing avenues. One of these is strain engineering of nanowires, implemented through the growth of asymmetrical heterostructures. Here, we report metal-organic molecular beam epitaxy of bent InP/InAs core/shell nanowires brought by precursor flow directionality in the growth chamber. We observe the increase of bending with decreased core diameter. We further analyze the composition of a single nanowire and show through supporting finite element simulations that strain accommodation following the lattice mismatch between InP and InAs dominates nanowire bending. The simulations show the interplay between material composition, shell thickness, and tapering in determining the bending. The simulation results are in good agreement with the experimental bending curvature, reproducing the radius of 4.3 µm (±10%), for the 2.3 µm long nanowire. The InP core of the bent heterostructure was found to be compressed at about 2%. This report provides evidence of shape control and strain engineering in nanostructures, specifically through the exchange of group-V materials in III-V nanowire growth.
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Affiliation(s)
- Ya'akov Greenberg
- Department of Electrical Engineering, Technion, Haifa 32000, Israel.
| | - Alexander Kelrich
- Department of Electrical Engineering, Technion, Haifa 32000, Israel.
| | - Shimon Cohen
- Department of Electrical Engineering, Technion, Haifa 32000, Israel.
| | - Sohini Kar-Narayan
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK.
| | - Dan Ritter
- Department of Electrical Engineering, Technion, Haifa 32000, Israel.
| | - Yonatan Calahorra
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK.
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13
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Abstract
Semiconductor nanowires have attracted extensive interest as one of the best-defined classes of nanoscale building blocks for the bottom-up assembly of functional electronic and optoelectronic devices over the past two decades. The article provides a comprehensive review of the continuing efforts in exploring semiconductor nanowires for the assembly of functional nanoscale electronics and macroelectronics. Specifically, we start with a brief overview of the synthetic control of various semiconductor nanowires and nanowire heterostructures with precisely controlled physical dimension, chemical composition, heterostructure interface, and electronic properties to define the material foundation for nanowire electronics. We then summarize a series of assembly strategies developed for creating well-ordered nanowire arrays with controlled spatial position, orientation, and density, which are essential for constructing increasingly complex electronic devices and circuits from synthetic semiconductor nanowires. Next, we review the fundamental electronic properties and various single nanowire transistor concepts. Combining the designable electronic properties and controllable assembly approaches, we then discuss a series of nanoscale devices and integrated circuits assembled from nanowire building blocks, as well as a unique design of solution-processable nanowire thin-film transistors for high-performance large-area flexible electronics. Last, we conclude with a brief perspective on the standing challenges and future opportunities.
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Affiliation(s)
- Chuancheng Jia
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Zhaoyang Lin
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Yu Huang
- Department of Materials Science and Engineering , University of California, Los Angeles , Los Angeles , California 90095 , United States.,California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Xiangfeng Duan
- Department of Chemistry and Biochemistry , University of California, Los Angeles , Los Angeles , California 90095 , United States.,California NanoSystems Institute , University of California, Los Angeles , Los Angeles , California 90095 , United States
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14
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Ren Y, Leubner P, Verheijen MA, Haverkort JEM, Bakkers EPAM. Hexagonal silicon grown from higher order silanes. NANOTECHNOLOGY 2019; 30:295602. [PMID: 30840942 DOI: 10.1088/1361-6528/ab0d46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We demonstrate the merits of an unexplored precursor, tetrasilane (Si4H10), as compared to disilane (Si2H6) for the growth of defect-free, epitaxial hexagonal silicon (Si). We investigate the growth kinetics of hexagonal Si shells epitaxially around defect-free wurtzite gallium phosphide (GaP) nanowires. Two temperature regimes are identified, representing two different surface reaction mechanisms for both types of precursors. Growth in the low temperature regime (415 °C-600 °C) is rate limited by interaction between the Si surface and the adsorbates, and in the high temperature regime (600 °C-735 °C) by chemisorption. The activation energy of the Si shell growth is 2.4 ± 0.2 eV for Si2H6 and 1.5 ± 0.1 eV for Si4H10 in the low temperature regime. We observe inverse tapering of the Si shells and explain this phenomenon by a basic diffusion model where the substrate acts as a particle sink. Most importantly, we show that, by using Si4H10 as a precursor instead of Si2H6, non-tapered Si shells can be grown with at least 50 times higher growth rate below 460 °C. The lower growth temperature may help to reduce the incorporation of impurities resulting from the growth of GaP.
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Affiliation(s)
- Yizhen Ren
- Eindhoven University of Technology, Department of Applied Physics, Eindhoven, The Netherlands
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15
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Francaviglia L, Tütüncüoglu G, Matteini F, Morral AFI. Tuning adatom mobility and nanoscale segregation by twin formation and polytypism. NANOTECHNOLOGY 2019; 30:054006. [PMID: 30517084 DOI: 10.1088/1361-6528/aaefdd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Nanoscale variations in the composition of an Al x Ga1-x As shell around a GaAs nanowire affect the nanowire functionality and can lead to the formation of localized quantum emitters. These composition fluctuations can be the consequence of variations of crystal phase and/or nanoscale adatom mobility. By applying electron-microscopy-related techniques we correlate the optical, compositional and structural properties at the nanoscale on the same object. The results indicate a clear correlation between the twin density in the nanowire and the quantum-emitter density as well as a significant redshift in the emission. We propose that twinning increases nanoscale segregation effects in ternary alloys. An additional redshift in the emission can be explained by the staggered band alignment between wurtzite and zinc-blende phases. This work opens new avenues in the achievement of homogeneous ternary and quaternary alloys in nanowires and in the engineering of the segregation effects at the nanoscale.
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Affiliation(s)
- Luca Francaviglia
- Laboratoire des Matériaux Semiconducteurs, Institut des Matériaux, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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16
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Rodichkina SP, Lysenko V, Belarouci A, Bezverkhyy I, Chassagnon R, Isaiev M, Nychyporuk T, Timoshenko VY. Photo-induced cubic-to-hexagonal polytype transition in silicon nanowires. CrystEngComm 2019. [DOI: 10.1039/c9ce00562e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Crystalline phase transformation in silicon nanowires from cubic diamond to hexagonal diamond under strong laser excitation, caused by inhomogeneous heating-induced mechanical stresses.
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Affiliation(s)
- S. P. Rodichkina
- Lomonosov Moscow State University
- Faculty of Physics
- 119991 Moscow
- Russia
- University of Lyon
| | - V. Lysenko
- University of Lyon
- Nanotechnology Institute of Lyon
- UMR CNRS 5270
- INSA de Lyon
- France
| | - A. Belarouci
- University of Lyon
- Nanotechnology Institute of Lyon
- UMR CNRS 5270
- INSA de Lyon
- France
| | - I. Bezverkhyy
- Laboratoire Interdisciplinaire Carnot de Bourgogne
- UMR 6303 CNRS-Université de Bourgogne-Franche Comte
- 21078 Dijon Cedex
- France
| | - R. Chassagnon
- Laboratoire Interdisciplinaire Carnot de Bourgogne
- UMR 6303 CNRS-Université de Bourgogne-Franche Comte
- 21078 Dijon Cedex
- France
| | - M. Isaiev
- Taras Shevchenko National University of Kyiv
- Kiev 01601
- Ukraine
- Laboratoire LEMTA
- Faculte des Sciences et Technologies
| | - T. Nychyporuk
- University of Lyon
- Nanotechnology Institute of Lyon
- UMR CNRS 5270
- INSA de Lyon
- France
| | - V. Yu. Timoshenko
- Lomonosov Moscow State University
- Faculty of Physics
- 119991 Moscow
- Russia
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute)
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17
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Zeng H, Yu X, Fonseka HA, Gott JA, Tang M, Zhang Y, Boras G, Xu J, Sanchez AM, Liu H. Hybrid III-V/IV Nanowires: High-Quality Ge Shell Epitaxy on GaAs Cores. NANO LETTERS 2018; 18:6397-6403. [PMID: 30205011 DOI: 10.1021/acs.nanolett.8b02760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The integration of optically active III-V and electronic-suitable IV materials on the same nanowire could provide a great potential for the combination of photonics and electronics in the nanoscale. In this Letter, we demonstrate the growth of GaAs/Ge core-shell nanowires on Si substrates by molecular beam epitaxy and investigate the radial and axial Ge epitaxy on GaAs nanowires in detail. High-quality core-shell nanowires with smooth side facets and dislocation-free, sharp interfaces are achieved. It is found that the low shell growth temperature leads to smoother side facets, while higher shell growth temperatures lead to more relaxed structures with significantly faceted sidewalls. The possibility of forming a III-V/IV heterostructure nanowire with a Ge section development in the axial direction of a GaAs nanowire using a Ga droplet is also revealed. These nanowires provide an ideal platform for nanoscale III-V/IV combination, which is promising for highly integrated photonic and electronic hybrid devices on a single chip.
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Affiliation(s)
- Haotian Zeng
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
| | - Xuezhe Yu
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
| | - H Aruni Fonseka
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - James A Gott
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Mingchu Tang
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
| | - Yunyan Zhang
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
| | - Giorgos Boras
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
| | - Jia Xu
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
| | - Ana M Sanchez
- Department of Physics , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Huiyun Liu
- Department of Electronic and Electrical Engineering , University College London , London WC1E 7JE , United Kingdom
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18
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Gagliano L, Albani M, Verheijen MA, Bakkers EPAM, Miglio L. Twofold origin of strain-induced bending in core-shell nanowires: the GaP/InGaP case. NANOTECHNOLOGY 2018; 29:315703. [PMID: 29749960 DOI: 10.1088/1361-6528/aac417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Nanowires have emerged as a promising platform for the development of novel and high-quality heterostructures at large lattice misfit, inaccessible in a thin film configuration. However, despite core-shell nanowires allowing a very efficient elastic release of the misfit strain, the growth of highly uniform arrays of nanowire heterostructures still represents a challenge, for example due to a strain-induced bending morphology. Here we investigate the bending of wurtzite GaP/In x Ga1-x P core-shell nanowires using transmission electron microscopy and energy dispersive x-ray spectroscopy, both in terms of geometric and compositional asymmetry with respect to the longitudinal axis. We compare the experimental data with finite element method simulations in three dimensions, showing that both asymmetries are responsible for the actual bending. Such findings are valid for all lattice-mismatched core-shell nanowire heterostructures based on ternary alloys. Our work provides a quantitative understanding of the bending effect in general while also suggesting a strategy to minimise it.
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Affiliation(s)
- Luca Gagliano
- Dept. of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
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19
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Cartoixà X, Palummo M, Hauge HIT, Bakkers EPAM, Rurali R. Optical Emission in Hexagonal SiGe Nanowires. NANO LETTERS 2017; 17:4753-4758. [PMID: 28654293 DOI: 10.1021/acs.nanolett.7b01441] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Recent advances in the synthetic growth of nanowires have given access to crystal phases that in bulk are only observed under extreme pressure conditions. Here, we use first-principles methods based on density functional theory and many-body perturbation theory to show that a suitable mixing of hexagonal Si and hexagonal Ge yields a direct bandgap with an optically permitted transition. Comparison of the calculated radiative lifetimes with typical values of nonradiative recombination mechanisms indicates that optical emission will be the dominant recombination mechanism. These findings pave the way to the development of silicon-based optoelectronic devices, thus far hindered by the poor light emission efficiency of cubic Si.
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Affiliation(s)
- Xavier Cartoixà
- Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona , 08193 Bellaterra, Barcelona, Spain
| | - Maurizia Palummo
- Dipartimento di Fisica and INFN, Università di Roma "Tor Vergata" via della Ricerca Scientifica 1 , 00133 Roma, Italy
| | - Håkon Ikaros T Hauge
- Department of Applied Physics, TU Eindhoven , Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - Erik P A M Bakkers
- Department of Applied Physics, TU Eindhoven , Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - Riccardo Rurali
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra , 08193 Bellaterra, Barcelona, Spain
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20
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Ishizaka F, Hiraya Y, Tomioka K, Motohisa J, Fukui T. Growth of All-Wurtzite InP/AlInP Core-Multishell Nanowire Array. NANO LETTERS 2017; 17:1350-1355. [PMID: 28166409 DOI: 10.1021/acs.nanolett.6b03727] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrated the formation of all-wurtzite (WZ) InP/AlInP core-multishell (CMS) nanowires (NWs) by selective-area growth with the crystal structure transfer method. The CMS NWs consisting of an AlInP-based double heterostructure showed that the crystal structure of the multishell succeeded to the WZ phase from the WZ InP NW by the crystal structure transfer method. Transmission electron microscopy revealed that the core-shell interface had a few stacking faults due to lattice mismatch. In addition, lattice constants of WZ AlInP with a variation of Al content were determined by X-ray diffraction reciprocal space mappings, and the WZ AlInP shell had tensile strain along the c-axis. The WZ AlInP shells (Al content: 25-54%) showed cathode luminescence emissions at 1.6-2.1 eV, possibly related to In-rich domains due to composition fluctuation in the WZ AlInP shell.
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Affiliation(s)
- Fumiya Ishizaka
- Graduate School of Information Science and Technology, and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University , North 13 West 8, Sapporo 060-8628, Japan
| | - Yoshihiro Hiraya
- Graduate School of Information Science and Technology, and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University , North 13 West 8, Sapporo 060-8628, Japan
| | - Katsuhiro Tomioka
- Graduate School of Information Science and Technology, and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University , North 13 West 8, Sapporo 060-8628, Japan
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
| | - Junichi Motohisa
- Graduate School of Information Science and Technology, and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University , North 13 West 8, Sapporo 060-8628, Japan
| | - Takashi Fukui
- Graduate School of Information Science and Technology, and Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University , North 13 West 8, Sapporo 060-8628, Japan
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21
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Hauge HIT, Conesa-Boj S, Verheijen MA, Koelling S, Bakkers EPAM. Single-Crystalline Hexagonal Silicon-Germanium. NANO LETTERS 2017; 17:85-90. [PMID: 28001429 DOI: 10.1021/acs.nanolett.6b03488] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Group IV materials with the hexagonal diamond crystal structure have been predicted to exhibit promising optical and electronic properties. In particular, hexagonal silicon-germanium (Si1-xGex) should be characterized by a tunable direct band gap with implications ranging from Si-based light-emitting diodes to lasers and quantum dots for single photon emitters. Here we demonstrate the feasibility of high-quality defect-free and wafer-scale hexagonal Si1-xGex growth with precise control of the alloy composition and layer thickness. This is achieved by transferring the hexagonal phase from a GaP/Si core/shell nanowire template, the same method successfully employed by us to realize hexagonal Si. We determine the optimal growth conditions in order to achieve single-crystalline layer-by-layer Si1-xGex growth in the preferred stoichiometry region. Our results pave the way for exploiting the novel properties of hexagonal Si1-xGex alloys in technological applications.
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Affiliation(s)
- Håkon Ikaros T Hauge
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Sonia Conesa-Boj
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Marcel A Verheijen
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Philips Innovation Laboratories, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands
| | - Sebastian Koelling
- 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
- Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
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22
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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.
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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
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23
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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.
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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
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24
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Tian L, Di Mario L, Minotti A, Tiburzi G, Mendis BG, Zeze DA, Martelli F. Direct growth of Si nanowires on flexible organic substrates. NANOTECHNOLOGY 2016; 27:225601. [PMID: 27098523 DOI: 10.1088/0957-4484/27/22/225601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A key characteristic of semiconductor nanowires (NWs) is that they grow on any substrate that can withstand the growth conditions, paving the way for their use in flexible electronics. We report on the direct growth of crystalline silicon nanowires on polyimide substrates. The Si NWs are grown by plasma-enhanced chemical vapor deposition, which allows the growth to proceed at temperatures low enough to be compatible with plastic substrates (350 °C), where gold or indium are used as growth seeds. In is particularly interesting as the seed not only because it leads to a better NW crystal quality but also because it overcomes a core problem induced by the use of Au in silicon processing, i.e. Au creates deep carrier traps when incorporated in the nanowires.
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Affiliation(s)
- Lin Tian
- CNR-IMM, via del Fosso del Cavaliere, 100, I-00133 Roma, Italy
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25
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Swart I, Liljeroth P, Vanmaekelbergh D. Scanning probe microscopy and spectroscopy of colloidal semiconductor nanocrystals and assembled structures. Chem Rev 2016; 116:11181-219. [PMID: 26900754 DOI: 10.1021/acs.chemrev.5b00678] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Colloidal semiconductor nanocrystals become increasingly important in materials science and technology, due to their optoelectronic properties that are tunable by size. The measurement and understanding of their energy levels is key to scientific and technological progress. Here we review how the confined electronic orbitals and related energy levels of individual semiconductor quantum dots have been measured by means of scanning tunneling microscopy and spectroscopy. These techniques were originally developed for flat conducting surfaces, but they have been adapted to investigate the atomic and electronic structure of semiconductor quantum dots. We compare the results obtained on colloidal quantum dots with those on comparable solid-state ones. We also compare the results obtained with scanning tunneling spectroscopy with those of optical spectroscopy. The first three sections provide an introduction to colloidal quantum dots, and a theoretical basis to be able to understand tunneling spectroscopy on dots attached to a conducting surface. In sections 4 and 5 , we review the work performed on lead-chalcogenide nanocrystals and on colloidal quantum dots and rods of II-VI compounds, respectively. In section 6 , we deal with colloidal III-V nanocrystals and compare the results with their self-assembled counter parts. In section 7 , we review the work on other types of semiconductor quantum dots, especially on Si and Ge nanocrystals.
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Affiliation(s)
- Ingmar Swart
- Debye Institute for Nanomaterials Science, Chemistry Department, University of Utrecht , Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Peter Liljeroth
- Department of Applied Physics, Aalto University School of Science , PO Box 15100, 00076 Aalto, Finland
| | - Daniel Vanmaekelbergh
- Debye Institute for Nanomaterials Science, Chemistry Department, University of Utrecht , Princetonplein 5, 3584 CC Utrecht, The Netherlands
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26
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Hauge HIT, Verheijen MA, Conesa-Boj S, Etzelstorfer T, Watzinger M, Kriegner D, Zardo I, Fasolato C, Capitani F, Postorino P, Kölling S, Li A, Assali S, Stangl J, Bakkers EPAM. Hexagonal Silicon Realized. NANO LETTERS 2015; 15:5855-60. [PMID: 26230363 DOI: 10.1021/acs.nanolett.5b01939] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Silicon, arguably the most important technological semiconductor, is predicted to exhibit a range of new and interesting properties when grown in the hexagonal crystal structure. To obtain pure hexagonal silicon is a great challenge because it naturally crystallizes in the cubic structure. Here, we demonstrate the fabrication of pure and stable hexagonal silicon evidenced by structural characterization. In our approach, we transfer the hexagonal crystal structure from a template hexagonal gallium phosphide nanowire to an epitaxially grown silicon shell, such that hexagonal silicon is formed. The typical ABABAB... stacking of the hexagonal structure is shown by aberration-corrected imaging in transmission electron microscopy. In addition, X-ray diffraction measurements show the high crystalline purity of the material. We show that this material is stable up to 9 GPa pressure. With this development, we open the way for exploring its optical, electrical, superconducting, and mechanical properties.
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Affiliation(s)
| | - Marcel A Verheijen
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Philips Innovation Services, 5656 AE Eindhoven, The Netherlands
| | - Sonia Conesa-Boj
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
| | - Tanja Etzelstorfer
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , A-4040 Linz, Austria
| | - Marc Watzinger
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , A-4040 Linz, Austria
| | - Dominik Kriegner
- Department of Condensed Matter Physics, Charles University in Prague , Ke Karlovu 5, 121 16 Prague 2, Czech Republic
| | - Ilaria Zardo
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Claudia Fasolato
- CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza , Piazzale le Aldo Moro 5, I-00185 Rome, Italy
- Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia , V.le Regina Elena, 291-00185, Rome, Italy
| | - Francesco Capitani
- CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza , Piazzale le Aldo Moro 5, I-00185 Rome, Italy
| | - Paolo Postorino
- CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza , Piazzale le Aldo Moro 5, I-00185 Rome, Italy
- Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia , V.le Regina Elena, 291-00185, Rome, Italy
| | - Sebastian Kölling
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Ang Li
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Simone Assali
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - Julian Stangl
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , A-4040 Linz, Austria
| | - Erik P A M Bakkers
- Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
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27
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Mankin MN, Day RW, Gao R, No YS, Kim SK, McClelland AA, Bell DC, Park HG, Lieber CM. Facet-Selective Epitaxy of Compound Semiconductors on Faceted Silicon Nanowires. NANO LETTERS 2015; 15:4776-82. [PMID: 26057208 DOI: 10.1021/acs.nanolett.5b01721] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Integration of compound semiconductors with silicon (Si) has been a long-standing goal for the semiconductor industry, as direct band gap compound semiconductors offer, for example, attractive photonic properties not possible with Si devices. However, mismatches in lattice constant, thermal expansion coefficient, and polarity between Si and compound semiconductors render growth of epitaxial heterostructures challenging. Nanowires (NWs) are a promising platform for the integration of Si and compound semiconductors since their limited surface area can alleviate such material mismatch issues. Here, we demonstrate facet-selective growth of cadmium sulfide (CdS) on Si NWs. Aberration-corrected transmission electron microscopy analysis shows that crystalline CdS is grown epitaxially on the {111} and {110} surface facets of the Si NWs but that the Si{113} facets remain bare. Further analysis of CdS on Si NWs grown at higher deposition rates to yield a conformal shell reveals a thin oxide layer on the Si{113} facet. This observation and control experiments suggest that facet-selective growth is enabled by the formation of an oxide, which prevents subsequent shell growth on the Si{113} NW facets. Further studies of facet-selective epitaxial growth of CdS shells on micro-to-mesoscale wires, which allows tuning of the lateral width of the compound semiconductor layer without lithographic patterning, and InP shell growth on Si NWs demonstrate the generality of our growth technique. In addition, photoluminescence imaging and spectroscopy show that the epitaxial shells display strong and clean band edge emission, confirming their high photonic quality, and thus suggesting that facet-selective epitaxy on NW substrates represents a promising route to integration of compound semiconductors on Si.
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Affiliation(s)
| | | | | | - You-Shin No
- ∥Department of Physics, Korea University, Seoul 136-701, Republic of Korea
| | | | | | | | - Hong-Gyu Park
- ∥Department of Physics, Korea University, Seoul 136-701, Republic of Korea
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28
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Namazi L, Nilsson M, Lehmann S, Thelander C, Dick KA. Selective GaSb radial growth on crystal phase engineered InAs nanowires. NANOSCALE 2015; 7:10472-81. [PMID: 26006335 DOI: 10.1039/c5nr01165e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In this work we have developed InAs nanowire templates, with designed zinc blende and wurtzite segments, for selective growth of radial GaSb heterostructures using metal organic vapor phase epitaxy. We find that the radial growth rate of GaSb is determined by the crystal phase of InAs, and that growth is suppressed on InAs segments with a pure wurtzite crystal phase. The morphology and the thickness of the grown shell can be tuned with full control by the growth conditions. We demonstrate that multiple distinct core-shell segments can be designed and realized with precise control over their length and axial position. Electrical measurements confirm that suppression of shell growth is possible on segments with wurtzite structures. This growth method enables new functionalities in structures formed by using bottom-up techniques, with complexity beyond that attainable by using top-down techniques.
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Affiliation(s)
- Luna Namazi
- Solid State Physics, Lund University, Box 118, S-221 00 Lund, Sweden.
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29
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Treu J, Stettner T, Watzinger M, Morkötter S, Döblinger M, Matich S, Saller K, Bichler M, Abstreiter G, Finley JJ, Stangl J, Koblmüller G. Lattice-Matched InGaAs-InAlAs Core-Shell Nanowires with Improved Luminescence and Photoresponse Properties. NANO LETTERS 2015; 15:3533-40. [PMID: 25922974 PMCID: PMC4434527 DOI: 10.1021/acs.nanolett.5b00979] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 04/23/2015] [Indexed: 05/25/2023]
Abstract
Core-shell nanowires (NW) have become very prominent systems for band engineered NW heterostructures that effectively suppress detrimental surface states and improve performance of related devices. This concept is particularly attractive for material systems with high intrinsic surface state densities, such as the low-bandgap In-containing group-III arsenides, however selection of inappropriate, lattice-mismatched shell materials have frequently caused undesired strain accumulation, defect formation, and modifications of the electronic band structure. Here, we demonstrate the realization of closely lattice-matched radial InGaAs-InAlAs core-shell NWs tunable over large compositional ranges [x(Ga)∼y(Al) = 0.2-0.65] via completely catalyst-free selective-area molecular beam epitaxy. On the basis of high-resolution X-ray reciprocal space maps the strain in the NW core is found to be insignificant (ε < 0.1%), which is further reflected by the absence of strain-induced spectral shifts in luminescence spectra and nearly unmodified band structure. Remarkably, the lattice-matched InAlAs shell strongly enhances the optical efficiency by up to 2 orders of magnitude, where the efficiency enhancement scales directly with increasing band offset as both Ga- and Al-contents increase. Ultimately, we fabricated vertical InGaAs-InAlAs NW/Si photovoltaic cells and show that the enhanced internal quantum efficiency is directly translated to an energy conversion efficiency that is ∼3-4 times larger as compared to an unpassivated cell. These results highlight the promising performance of lattice-matched III-V core-shell NW heterostructures with significant impact on future development of related nanophotonic and electronic devices.
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Affiliation(s)
- Julian Treu
- Walter Schottky Institut, Physik Department, and Center
of Nanotechnology and Nanomaterials, Technische
Universität München, Am Coulombwall 4, Garching, 85748, Germany
- Nanosystems Initiative
Munich (NIM), Schellingstrasse
4, München, 80799, Germany
| | - Thomas Stettner
- Walter Schottky Institut, Physik Department, and Center
of Nanotechnology and Nanomaterials, Technische
Universität München, Am Coulombwall 4, Garching, 85748, Germany
| | - Marc Watzinger
- Institute of Semiconductor and Solid State
Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, Linz, 4040, Austria
| | - Stefanie Morkötter
- Walter Schottky Institut, Physik Department, and Center
of Nanotechnology and Nanomaterials, Technische
Universität München, Am Coulombwall 4, Garching, 85748, Germany
| | - Markus Döblinger
- Deparment of Chemistry, Ludwig-Maximilian
Universität München, Butenandtstrasse 5-13, München, 81377, Germany
| | - Sonja Matich
- Walter Schottky Institut, Physik Department, and Center
of Nanotechnology and Nanomaterials, Technische
Universität München, Am Coulombwall 4, Garching, 85748, Germany
| | - Kai Saller
- Walter Schottky Institut, Physik Department, and Center
of Nanotechnology and Nanomaterials, Technische
Universität München, Am Coulombwall 4, Garching, 85748, Germany
| | - Max Bichler
- Walter Schottky Institut, Physik Department, and Center
of Nanotechnology and Nanomaterials, Technische
Universität München, Am Coulombwall 4, Garching, 85748, Germany
| | - Gerhard Abstreiter
- Walter Schottky Institut, Physik Department, and Center
of Nanotechnology and Nanomaterials, Technische
Universität München, Am Coulombwall 4, Garching, 85748, Germany
- Nanosystems Initiative
Munich (NIM), Schellingstrasse
4, München, 80799, Germany
- Institute
for Advanced Study, Technische Universität
München, Lichtenbergstraße
2a, Garching, 85748, Germany
| | - Jonathan J. Finley
- Walter Schottky Institut, Physik Department, and Center
of Nanotechnology and Nanomaterials, Technische
Universität München, Am Coulombwall 4, Garching, 85748, Germany
- Nanosystems Initiative
Munich (NIM), Schellingstrasse
4, München, 80799, Germany
| | - Julian Stangl
- Institute of Semiconductor and Solid State
Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, Linz, 4040, Austria
| | - Gregor Koblmüller
- Walter Schottky Institut, Physik Department, and Center
of Nanotechnology and Nanomaterials, Technische
Universität München, Am Coulombwall 4, Garching, 85748, Germany
- Nanosystems Initiative
Munich (NIM), Schellingstrasse
4, München, 80799, Germany
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30
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Conesa-Boj S, Hauge HIT, Verheijen MA, Assali S, Li A, Bakkers EPAM, Fontcuberta i Morral A. Cracking the Si Shell Growth in Hexagonal GaP-Si Core-Shell Nanowires. NANO LETTERS 2015; 15:2974-2979. [PMID: 25922878 DOI: 10.1021/nl504813e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Semiconductor nanowires have increased the palette of possible heterostructures thanks to their more effective strain relaxation. Among these, core-shell heterostructures are much more sensitive to strain than axial ones. It is now accepted that the formation of misfit dislocations depends both on the lattice mismatch and relative dimensions of the core and the shell. Here, we show for the first time the existence of a new kind of defect in core-shell nanowires: cracks. These defects do not originate from a lattice mismatch (we demonstrate their appearance in an essentially zero-mismatch system) but from the thermal history during the growth of the nanowires. Crack defects lead to the development of secondary defects, such as type-I1 stacking faults and Frank-type dislocations. These results provide crucial information with important implications for the optimized synthesis of nanowire-based core-shell heterostructures.
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Affiliation(s)
- S Conesa-Boj
- †École Polytechnique Fédérale de Lausanne (EPFL), Laboratoire des Matériaux Semiconducteurs (LMSC), 1015 Lausanne, Switzerland
| | - 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
- §Philips Innovation Services Eindhoven, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands
| | - S Assali
- ‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - A Li
- ‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - E P A M Bakkers
- ‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- ∥Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - A Fontcuberta i Morral
- †École Polytechnique Fédérale de Lausanne (EPFL), Laboratoire des Matériaux Semiconducteurs (LMSC), 1015 Lausanne, Switzerland
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31
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Li Y, Liu Z, Lu X, Su Z, Wang Y, Liu R, Wang D, Jian J, Lee JH, Wang H, Yu Q, Bao J. Broadband infrared photoluminescence in silicon nanowires with high density stacking faults. NANOSCALE 2015; 7:1601-5. [PMID: 25510619 DOI: 10.1039/c4nr05410e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Making silicon an efficient light-emitting material is an important goal of silicon photonics. Here we report the observation of broadband sub-bandgap photoluminescence in silicon nanowires with a high density of stacking faults. The photoluminescence becomes stronger and exhibits a blue shift under higher laser powers. The super-linear dependence on excitation intensity indicates a strong competition between radiative and defect-related non-radiative channels, and the spectral blue shift is ascribed to the band filling effect in the heterostructures of wurtzite silicon and cubic silicon created by stacking faults.
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Affiliation(s)
- Yang Li
- Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77204, USA.
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32
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Vincent L, Patriarche G, Hallais G, Renard C, Gardès C, Troadec D, Bouchier D. Novel heterostructured Ge nanowires based on polytype transformation. NANO LETTERS 2014; 14:4828-4836. [PMID: 24988041 DOI: 10.1021/nl502049a] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report on a strain-induced phase transformation in Ge nanowires under external shear stresses. The resulted polytype heterostructure may have great potential for photonics and thermoelectric applications. ⟨111⟩-oriented Ge nanowires with standard diamond structure (3C) undergo a phase transformation toward the hexagonal diamond phase referred as the 2H-allotrope. The phase transformation occurs heterogeneously on shear bands along the length of the nanowire. The structure meets the common phenomenological criteria of a martensitic phase transformation. This point is discussed to initiate an on going debate on the transformation mechanisms. The process results in unprecedented quasiperiodic heterostructures 3C/2H along the Ge nanowire. The thermal stability of those 2H domains is also studied under annealing up to 650 °C by in situ TEM.
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Affiliation(s)
- Laetitia Vincent
- Univ. Paris-Sud, Institut d'Electronique Fondamentale , UMR 8622, Orsay F-91405, France
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33
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Jadczak J, Plochocka P, Mitioglu A, Breslavetz I, Royo M, Bertoni A, Goldoni G, Smolenski T, Kossacki P, Kretinin A, Shtrikman H, Maude DK. Unintentional high-density p-type modulation doping of a GaAs/AlAs core-multishell nanowire. NANO LETTERS 2014; 14:2807-2814. [PMID: 24745828 DOI: 10.1021/nl500818k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Achieving significant doping in GaAs/AlAs core/shell nanowires (NWs) is of considerable technological importance but remains a challenge due to the amphoteric behavior of the dopant atoms. Here we show that placing a narrow GaAs quantum well in the AlAs shell effectively getters residual carbon acceptors leading to an unintentional p-type doping. Magneto-optical studies of such a GaAs/AlAs core-multishell NW reveal quantum confined emission. Theoretical calculations of NW electronic structure confirm quantum confinement of carriers at the core/shell interface due to the presence of ionized carbon acceptors in the 1 nm GaAs layer in the shell. Microphotoluminescence in high magnetic field shows a clear signature of avoided crossings of the n = 0 Landau level emission line with the n = 2 Landau level TO phonon replica. The coupling is caused by the resonant hole-phonon interaction, which points to a large two-dimensional hole density in the structure.
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Affiliation(s)
- J Jadczak
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA , 143, avenue de Rangueil, 31400 Toulouse, France
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34
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Weiss M, Kinzel JB, Schülein FJR, Heigl M, Rudolph D, Morkötter S, Döblinger M, Bichler M, Abstreiter G, Finley JJ, Koblmüller G, Wixforth A, Krenner HJ. Dynamic acoustic control of individual optically active quantum dot-like emission centers in heterostructure nanowires. NANO LETTERS 2014; 14:2256-2264. [PMID: 24678960 DOI: 10.1021/nl4040434] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We probe and control the optical properties of emission centers forming in radial heterostructure GaAs-Al0.3Ga0.7As nanowires and show that these emitters, located in Al0.3Ga0.7As layers, can exhibit quantum-dot like characteristics. We employ a radio frequency surface acoustic wave to dynamically control their emission energy, and occupancy state on a nanosecond time scale. In the spectral oscillations, we identify unambiguous signatures arising from both the mechanical and electrical component of the surface acoustic wave. In addition, different emission lines of a single emission center exhibit pronounced anticorrelated intensity oscillations during the acoustic cycle. These arise from a dynamically triggered carrier extraction out of the emission center to a continuum in the radial heterostructure. Using finite element modeling and Wentzel-Kramers-Brillouin theory we identify quantum tunneling as the underlying mechanism. These simulation results quantitatively reproduce the observed switching and show that in our systems these emission centers are spatially separated from the continuum by >10.5 nm.
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Affiliation(s)
- Matthias Weiss
- Lehrstuhl für Experimentalphysik 1 and Augsburg Centre for Innovative Technologies (ACIT), Universität Augsburg , Universitätsstraße 1, 86159 Augsburg, Germany
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35
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Espinal AE, Yan Y, Zhang L, Espinal L, Morey A, Wells BO, Aindow M, Suib SL. Substrate control of anisotropic resistivity in heteroepitaxial nanostructured arrays of cryptomelane manganese oxide on strontium titanate. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:66-72. [PMID: 23894065 DOI: 10.1002/smll.201300713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Indexed: 06/02/2023]
Abstract
Resistivity and resistance measurements have been carried out for thin films of cryptomelane-type manganese oxide (OMS-2) grown onto (001), (110), and (111)STO single crystals substrates via pulsed laser deposition. While the symmetries of the (001) and (111)STO substrate surfaces give deposits consisting of multiple nanofiber arrays with isotropic in-plane resistivities, only a single nanofiber array is formed on (110)STO giving highly anisotropic electrical properties with very low resistivity values measured parallel to the fibers and similar to the lowest value ever reported.
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Affiliation(s)
- Anais E Espinal
- Institute of Materials Science, University of Connecticut, Storrs, CT, USA
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36
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Aparna A, Brahmajirao V, Karthikeyan T. Review on Synthesis and Characterization of Gallium Phosphide. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.mspro.2014.07.150] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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37
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Conesa-Boj S, Boioli F, Russo-Averchi E, Dunand S, Heiss M, Rüffer D, Wyrsch N, Ballif C, Miglio L, Fontcuberta i Morral A. Plastic and elastic strain fields in GaAs/Si core-shell nanowires. NANO LETTERS 2014; 14:1859-64. [PMID: 24564880 DOI: 10.1021/nl4046312] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Thanks to their unique morphology, nanowires have enabled integration of materials in a way that was not possible before with thin film technology. In turn, this opens new avenues for applications in the areas of energy harvesting, electronics, and optoelectronics. This is particularly true for axial heterostructures, while core-shell systems are limited by the appearance of strain-induced dislocations. Even more challenging is the detection and understanding of these defects. We combine geometrical phase analysis with finite element strain simulations to quantify and determine the origin of the lattice distortion in core-shell nanowire structures. Such combination provides a powerful insight in the origin and characteristics of edge dislocations in such systems and quantifies their impact with the strain field map. We apply the method to heterostructures presenting single and mixed crystalline phase. Mixing crystalline phases along a nanowire turns out to be beneficial for reducing strain in mismatched core-shell structures.
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Affiliation(s)
- Sònia Conesa-Boj
- Laboratoire des Matériaux Semiconducteurs (LMSC)and ‡Institute of Microengineering (IMT), Photovoltaics and Thin Film Electronics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL) , 1015 Lausanne, Switzerland
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38
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Ghalamestani SG, Munshi AM, Dheeraj DL, Fimland BO, Weman H, Dick KA. Self-catalyzed MBE grown GaAs/GaAs(x)Sb(1-x) core-shell nanowires in ZB and WZ crystal structures. NANOTECHNOLOGY 2013; 24:405601. [PMID: 24028926 DOI: 10.1088/0957-4484/24/40/405601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We have investigated the growth of self-catalyzed GaAs/GaAs(x)Sb(1-x) core-shell nanowires directly on Si(111) substrates by molecular beam epitaxy. The compositions of the GaAs(x)Sb(1-x) shells are tuned in a wide range where the Sb-content is varied from 10 to ~70%, covering the miscibility gap. In addition, the GaAs(x)Sb(1-x) shells are grown on both zinc blende (ZB) and wurtzite (WZ) crystal structures. Morphological and structural characterizations of the grown nanowires indicate successful transfer of the GaAs core crystal structure to the GaAs(x)Sb(1-x) shells for both ZB and WZ nanowires, with slower shell growth rate on the WZ segments.
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39
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Carenco S, Portehault D, Boissière C, Mézailles N, Sanchez C. Nanoscaled Metal Borides and Phosphides: Recent Developments and Perspectives. Chem Rev 2013; 113:7981-8065. [DOI: 10.1021/cr400020d] [Citation(s) in RCA: 756] [Impact Index Per Article: 68.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Sophie Carenco
- Chimie de la Matière Condensée de Paris, UPMC Univ Paris 06, UMR 7574, Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France
- Chimie de la Matière Condensée de Paris, CNRS, UMR 77574, Collège de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France
- Chimie de la Matière Condensée de Paris, Collège de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France
- Laboratory Heteroelements and Coordination, Chemistry Department, Ecole Polytechnique, CNRS-UMR 7653, Palaiseau, France
| | - David Portehault
- Chimie de la Matière Condensée de Paris, UPMC Univ Paris 06, UMR 7574, Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France
- Chimie de la Matière Condensée de Paris, CNRS, UMR 77574, Collège de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France
- Chimie de la Matière Condensée de Paris, Collège de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France
| | - Cédric Boissière
- Chimie de la Matière Condensée de Paris, UPMC Univ Paris 06, UMR 7574, Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France
- Chimie de la Matière Condensée de Paris, CNRS, UMR 77574, Collège de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France
- Chimie de la Matière Condensée de Paris, Collège de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France
| | - Nicolas Mézailles
- Laboratory Heteroelements and Coordination, Chemistry Department, Ecole Polytechnique, CNRS-UMR 7653, Palaiseau, France
| | - Clément Sanchez
- Chimie de la Matière Condensée de Paris, UPMC Univ Paris 06, UMR 7574, Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France
- Chimie de la Matière Condensée de Paris, CNRS, UMR 77574, Collège de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France
- Chimie de la Matière Condensée de Paris, Collège de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France
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40
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Shin N, Chi M, Howe JY, Filler MA. Rational defect introduction in silicon nanowires. NANO LETTERS 2013; 13:1928-1933. [PMID: 23577694 DOI: 10.1021/nl3042728] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The controlled introduction of planar defects, particularly twin boundaries and stacking faults, in group IV nanowires remains challenging despite the prevalence of these structural features in other nanowire systems (e.g., II-VI and III-V). Here we demonstrate how user-programmable changes to precursor pressure and growth temperature can rationally generate both transverse twin boundaries and angled stacking faults during the growth of <111> oriented Si nanowires. We leverage this new capability to demonstrate prototype defect superstructures. These findings yield important insight into the mechanism of defect generation in semiconductor nanowires and suggest new routes to engineer the properties of this ubiquitous semiconductor.
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Affiliation(s)
- Naechul Shin
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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41
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Rudolph D, Funk S, Döblinger M, Morkötter S, Hertenberger S, Schweickert L, Becker J, Matich S, Bichler M, Spirkoska D, Zardo I, Finley JJ, Abstreiter G, Koblmüller G. Spontaneous alloy composition ordering in GaAs-AlGaAs core-shell nanowires. NANO LETTERS 2013; 13:1522-7. [PMID: 23517063 DOI: 10.1021/nl3046816] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
By employing various high-resolution metrology techniques we directly probe the material composition profile within GaAs-Al0.3Ga0.7As core-shell nanowires grown by molecular beam epitaxy on silicon. Micro Raman measurements performed along the entire (>10 μm) length of the [111]-oriented nanowires reveal excellent average compositional homogeneity of the nominally Al0.3Ga0.7As shell. In strong contrast, along the radial direction cross-sectional scanning transmission electron microscopy and associated chemical analysis reveal rich structure in the AlGaAs alloy composition due to interface segregation, nanofaceting, and local alloy fluctuations. Most strikingly, we observe a 6-fold Al-rich substructure along the corners of the hexagonal AlGaAs shell where the Al-content is up to x ~ 0.6, a factor of 2 larger than the body of the AlGaAs shell. This is associated with facet-dependent capillarity diffusion due to the nonplanarity of shell growth. A modulation of the Al-content is also found along the radial [110] growth directions of the AlGaAs shell. Besides the ~10(3)-fold enhancement of the photoluminescence yield due to inhibition of nonradiative surface recombination, the AlGaAs shell gives rise to a broadened band of sharp-line luminescence features extending ~150-30 meV below the band gap of Al0.3Ga0.7As. These features are attributed to deep level defects under influence of the observed local alloy fluctuations in the shell.
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Affiliation(s)
- Daniel Rudolph
- Walter Schottky Institut, Physik Department, Technische Universität München, Garching, Germany
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42
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Assali S, Zardo I, Plissard S, Kriegner D, Verheijen MA, Bauer G, Meijerink A, Belabbes A, Bechstedt F, Haverkort JEM, Bakkers EPAM. Direct band gap wurtzite gallium phosphide nanowires. NANO LETTERS 2013; 13:1559-63. [PMID: 23464761 PMCID: PMC3624814 DOI: 10.1021/nl304723c] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/20/2013] [Indexed: 05/27/2023]
Abstract
The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555-690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality.
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Affiliation(s)
- S. Assali
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
| | - I. Zardo
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
| | - S. Plissard
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
| | - D. Kriegner
- Institute
of Semiconductor and
Solid State Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - M. A. Verheijen
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
- Philips Innovation
Services Eindhoven, High Tech Campus 11, 5656AE Eindhoven,
The Netherlands
| | - G. Bauer
- Institute
of Semiconductor and
Solid State Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - A. Meijerink
- Debye Institute, Utrecht University, Princetonplein 1, 3500TA Utrecht,
The Netherlands
| | - A. Belabbes
- Institut
für Festkörpertheorie
und −optik, Friedrich Schiller Universität, 07743 Jena, Germany
| | - F. Bechstedt
- Institut
für Festkörpertheorie
und −optik, Friedrich Schiller Universität, 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
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43
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Paniagua-Domínguez R, Abujetas DR, Sánchez-Gil JA. Ultra low-loss, isotropic optical negative-index metamaterial based on hybrid metal-semiconductor nanowires. Sci Rep 2013; 3:1507. [PMID: 23514968 PMCID: PMC3604707 DOI: 10.1038/srep01507] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 03/06/2013] [Indexed: 11/13/2022] Open
Abstract
Recently, many fascinating properties predicted for metamaterials (negative refraction, superlensing, electromagnetic cloaking,…) were experimentally demonstrated. Unfortunately, the best achievements have no direct translation to the optical domain, without being burdened by technological and conceptual difficulties. Of particular importance within the realm of optical negative-index metamaterials (NIM), is the issue of simultaneously achieving strong electric and magnetic responses and low associated losses. Here, hybrid metal-semiconductor nanowires are proposed as building blocks of optical NIMs. The metamaterial thus obtained, highly isotropic in the plane normal to the nanowires, presents a negative index of refraction in the near-infrared, with values of the real part well below -1, and extremely low losses (an order of magnitude better than present optical NIMs). Tunability of the system allows to select the operating range in the whole telecom spectrum. The design is proven in configurations such as prisms and slabs, directly observing negative refraction.
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Affiliation(s)
- R. Paniagua-Domínguez
- Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid, Spain
| | - D. R. Abujetas
- Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid, Spain
| | - J. A. Sánchez-Gil
- Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid, Spain
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44
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Growth and optical properties of axial hybrid III–V/silicon nanowires. Nat Commun 2012; 3:1266. [DOI: 10.1038/ncomms2277] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 11/09/2012] [Indexed: 11/09/2022] Open
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45
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Convertino A, Cuscunà M, Martelli F. Silicon nanotubes from sacrificial silicon nanowires: fabrication and manipulation via embedding in flexible polymers. NANOTECHNOLOGY 2012; 23:305602. [PMID: 22781505 DOI: 10.1088/0957-4484/23/30/305602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In the present work we report a simple method to fabricate Si nanotubes (NTs) starting from the growth of self-assembled sacrificial Si nanowires that, at the same time, embeds them into a polyimide matrix, allowing a very easy manipulation of these nano-objects, including removal, transfer and positioning. Our all-silicon fabrication method is completely compatible with the Si technology platform and is therefore implementable using the existing technology. Transferred NTs show good electrical contact with underlying electrodes, and relatively low resistance values have been measured. All these features demonstrate the effectiveness of the transfer method and the potentiality of the NTs in electronics. Finally, optical reflectivity of the NTs has been measured in the near UV-near IR spectral range.
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46
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Johansson J, Bolinsson J, Ek M, Caroff P, Dick KA. Combinatorial approaches to understanding polytypism in III-V nanowires. ACS NANO 2012; 6:6142-9. [PMID: 22681568 DOI: 10.1021/nn301477x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Polytypism in III-V semiconductor nanowires is a topic that has received considerable attention in recent years. Achieving a pure nanowire crystal phase requires well-controlled and advanced parameter tuning for most III-V materials. Additionally, the new and unusual phases sometimes observed may present unique material properties if they can be controllably fabricated. With the prospect of using nanowires in applications within several different fields (including electronics, photonics, and life science), theoretical models are necessary to explain experimental trends and to attain a high level of crystal phase control. At present, there is no theoretical model (or combination of models) that fully explains how and why nanowire crystal structures commonly include several different polytypes. Here we use combinatorics and interlayer interactions to include higher order polytypes (4H and 6H) with the aim to explain nanowire crystal structure beyond the well-investigated zinc blende-wurtzite polytypism. Predictions from our theoretical models compare well with experimental results.
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Affiliation(s)
- Jonas Johansson
- Solid State Physics, Lund University, Box 118, S-22100 Lund, Sweden.
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47
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Hemesath ER, Schreiber DK, Kisielowski CF, Petford-Long AK, Lauhon LJ. Atomic structural analysis of nanowire defects and polytypes enabled through cross-sectional lattice imaging. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:1717-1724. [PMID: 22447661 DOI: 10.1002/smll.201102404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 01/12/2012] [Indexed: 05/31/2023]
Abstract
Correlated transmission electron microscopy imaging, electron diffraction, and Raman spectroscopy are used to investigate the structure of Si nanowires with planar defects. In addition to plan-view imaging, individual defective nanowires are imaged in axial cross-section at specific locations selected in plan-view imaging. This correlated characterization approach enables definitive identification of complex defect structures that give rise to diffraction patterns that have been misinterpreted in the literature. Conclusive evidence for the 9R Si polytype is presented, and the atomic structure of this phase is correlated with kinematically-forbidden reflections in Si diffraction patterns. Despite striking similarities between imaging and diffraction data from twinned nanowires and the 9R polytype, clear distinctions between the structures can be made. Finally, the structural origins of ⅓{422} reflections in Si [111] diffraction patterns are identified.
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Affiliation(s)
- Eric R Hemesath
- Department of Materials Science and Engineering, Northwestern University, 2220 N Campus Dr., Evanston IL 60208, USA
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48
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de la Mata M, Magen C, Gazquez J, Utama MIB, Heiss M, Lopatin S, Furtmayr F, Fernández-Rojas CJ, Peng B, Morante JR, Rurali R, Eickhoff M, Fontcuberta i Morral A, Xiong Q, Arbiol J. Polarity assignment in ZnTe, GaAs, ZnO, and GaN-AlN nanowires from direct dumbbell analysis. NANO LETTERS 2012; 12:2579-2586. [PMID: 22493937 DOI: 10.1021/nl300840q] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Aberration corrected scanning transmission electron microscopy (STEM) with high angle annular dark field (HAADF) imaging and the newly developed annular bright field (ABF) imaging are used to define a new guideline for the polarity determination of semiconductor nanowires (NWs) from binary compounds in two extreme cases: (i) when the dumbbell is formed with atoms of similar mass (GaAs) and (ii) in the case where one of the atoms is extremely light (N or O: ZnO and GaN/AlN). The theoretical fundaments of these procedures allow us to overcome the main challenge in the identification of dumbbell polarity. It resides in the separation and identification of the constituent atoms in the dumbbells. The proposed experimental via opens new routes for the fine characterization of nanostructures, e.g., in electronic and optoelectronic fields, where the polarity is crucial for the understanding of their physical properties (optical and electronic) as well as their growth mechanisms.
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Affiliation(s)
- Maria de la Mata
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, E-08193 Bellaterra, CAT, Spain
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49
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Xu T, Dick KA, Plissard S, Nguyen TH, Makoudi Y, Berthe M, Nys JP, Wallart X, Grandidier B, Caroff P. Faceting, composition and crystal phase evolution in III-V antimonide nanowire heterostructures revealed by combining microscopy techniques. NANOTECHNOLOGY 2012; 23:095702. [PMID: 22322440 DOI: 10.1088/0957-4484/23/9/095702] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
III-V antimonide nanowires are among the most interesting semiconductors for transport physics, nanoelectronics and long-wavelength optoelectronic devices due to their optimal material properties. In order to investigate their complex crystal structure evolution, faceting and composition, we report a combined scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning tunneling microscopy (STM) study of gold-nucleated ternary InAs/InAs(1-x)Sb(x) nanowire heterostructures grown by molecular beam epitaxy. SEM showed the general morphology and faceting, TEM revealed the internal crystal structure and ternary compositions, while STM was successfully applied to characterize the oxide-free nanowire sidewalls, in terms of nanofaceting morphology, atomic structure and surface composition. The complementary use of these techniques allows for correlation of the morphological and structural properties of the nanowires with the amount of Sb incorporated during growth. The addition of even a minute amount of Sb to InAs changes the crystal structure from perfect wurtzite to perfect zinc blende, via intermediate stacking fault and pseudo-periodic twinning regimes. Moreover, the addition of Sb during the axial growth of InAs/InAs(1-x)Sb(x) heterostructure nanowires causes a significant conformal lateral overgrowth on both segments, leading to the spontaneous formation of a core-shell structure, with an Sb-rich shell.
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Affiliation(s)
- Tao Xu
- Institut d'Electronique, de Microélectronique et de Nanotechnologie, UMR CNRS 8520, Villeneuve d'Ascq, France
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50
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den Hertog MI, Cayron C, Gentile P, Dhalluin F, Oehler F, Baron T, Rouviere JL. Hidden defects in silicon nanowires. NANOTECHNOLOGY 2012; 23:025701. [PMID: 22166492 DOI: 10.1088/0957-4484/23/2/025701] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recent publications have reported the presence of hexagonal phases in Si nanowires. Most of these reports were based on 'odd' diffraction patterns and HRTEM images—'odd' means that these images and diffraction patterns could not be obtained on perfect silicon crystals in the classical diamond cubic structure. We analyze the origin of these 'odd' patterns and images by studying the case of various Si nanowires grown using either Ni or Au as catalysts in combination with P or Al doping. Two models could explain the experimental results: (i) the presence of a hexagonal phase or (ii) the presence of defects that we call 'hidden' defects because they cannot be directly observed in most images. We show that in many cases one direction of observation is not sufficient to distinguish between the two models. Several directions of observations have to be used. Secondly, conventional TEM images, i.e. bright-field two-beam and dark-field images, are of great value in the identification of 'hidden' defects. In addition, slices of nanowires perpendicular to the growth axis can be very useful. In the studied nanowires no hexagonal phase with long range order is found and the 'odd' images and diffraction patterns are mostly due to planar defects causing superposition of different crystal grains. Finally, we show that in Raman experiments the defect-rich NWs can give rise to a Raman peak shifted to 504–511 cm⁻¹ with respect to the Si bulk peak at 520 cm⁻¹, indicating that Raman cannot be used to identify a hexagonal phase.
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Affiliation(s)
- M I den Hertog
- CEA-INAC/UJF-Grenoble1 UMR-E, SP2M, LEMMA, PFNC-Minatec, 17 rue des Martyrs, F-38054 Grenoble, France
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