1
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Si Z, Liu Z, Hu Y, Wang X, Xu C, Zheng S, Dong X, Gao X, Chen J, Wang J, Xu K. Yellow-Green Luminescence Due to Polarity-Dependent Incorporation of Carbon Impurities in Self-Assembled GaN Microdisk. NANO LETTERS 2022; 22:8670-8678. [PMID: 36256439 DOI: 10.1021/acs.nanolett.2c03274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Yellow-green luminescence (YGL) competes with near-bandgap emission (NBE) for carrier recombination channels, thereby reducing device efficiency; yet uncovering the origin of YGL remains a major challenge. In this paper, nearly stress-free and low dislocation density self-assembled GaN microdisks were synthesized by Na-flux method. The YGL of GaN microdisks highly depend on their polar facets. Variable accelerating voltage/power CL, variable temperature PL, and Raman spectroscopy are further performed to clarify the origin of polarity dependence of GaN microdisk YGL behavior, which indicates its independence of dislocations, surface effects, stress, crystalline quality, and gallium vacancies. It was found that the incorporation ability of carbon impurities in the polar (0001) facet is greater than that in the semipolar (101̅1) facets, producing higher content of CN or CNON defects, resulting in a more pronounced YGL in the polar (0001) facet of GaN.
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Affiliation(s)
- Zhiwei Si
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, Jiangsu, China
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, Anhui, China
- Shenyang National Laboratory for Materials Science, Jiangsu Institute of Advanced Semiconductors, NW-20, Nanopolis Suzhou, 99 Jinji Lake Avenue, Suzhou Industrial Park, Suzhou 215123, Jiangsu, China
| | - Zongliang Liu
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, Jiangsu, China
- Shenyang National Laboratory for Materials Science, Jiangsu Institute of Advanced Semiconductors, NW-20, Nanopolis Suzhou, 99 Jinji Lake Avenue, Suzhou Industrial Park, Suzhou 215123, Jiangsu, China
| | - Yaoqiao Hu
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Xiaoxuan Wang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Chunxiang Xu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Shunan Zheng
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, Jiangsu, China
| | - Xiaoming Dong
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, Jiangsu, China
| | - Xiaodong Gao
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, Jiangsu, China
| | - Jingjing Chen
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, Jiangsu, China
| | - Jianfeng Wang
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, Jiangsu, China
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, Anhui, China
- Suzhou Nanowin Science and Technology Co, Ltd., Suzhou 215123, Jiangsu, China
- Shenyang National Laboratory for Materials Science, Jiangsu Institute of Advanced Semiconductors, NW-20, Nanopolis Suzhou, 99 Jinji Lake Avenue, Suzhou Industrial Park, Suzhou 215123, Jiangsu, China
| | - Ke Xu
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, Jiangsu, China
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, Anhui, China
- Suzhou Nanowin Science and Technology Co, Ltd., Suzhou 215123, Jiangsu, China
- Shenyang National Laboratory for Materials Science, Jiangsu Institute of Advanced Semiconductors, NW-20, Nanopolis Suzhou, 99 Jinji Lake Avenue, Suzhou Industrial Park, Suzhou 215123, Jiangsu, China
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2
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Jin S, Shao W, Luo X, Wang H, Sun X, He X, Zhang X, Xie Y. Spatial Band Separation in a Surface Doped Heterolayered Structure for Realizing Efficient Singlet Oxygen Generation. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2206516. [PMID: 36134529 DOI: 10.1002/adma.202206516] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Singlet oxygen (1 O2 ) with electrical neutrality and long lifetime holds great promise in producing high-added-value chemicals via a selective oxidation reaction. However, photocatalytic 1 O2 generation via the charge-transfer mechanism still suffers from low efficiency due to the mismatched redox capacities and low concentration of photogenerated carriers in confined systems. Herein, by taking bismuth oxysilicate (Bi2 O2 SiO3 ) with alternating heterogeneous layered structure as a model, it is shown that iodine doping can facilitate the spatial redistributions of bands on alternated [Bi2 O2 ] and [SiO3 ] layers, which can promote the separation and transfer of photogenerated charge carriers. Meanwhile, the band positions of Bi2 O2 SiO3 are optimized to match the redox potential of 1 O2 generation. Benefiting from these features, iodine-doped Bi2 O2 SiO3 exhibits efficient 1 O2 generation with respect to its pristine counterpart, leading to promoted performance in the selective sulfide oxidation reaction. A new strategy is offered here for optimizing charge-transfer-mediated 1 O2 generation.
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Affiliation(s)
- Sen Jin
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Wei Shao
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Xiao Luo
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Hui Wang
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
- Institute of Energy, Hefei Comprehensive National Science Center, Hefei, Anhui, 230031, P. R. China
| | - Xianshun Sun
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Xin He
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Xiaodong Zhang
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
- Institute of Energy, Hefei Comprehensive National Science Center, Hefei, Anhui, 230031, P. R. China
| | - Yi Xie
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
- Institute of Energy, Hefei Comprehensive National Science Center, Hefei, Anhui, 230031, P. R. China
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3
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Luna M, Barawi M, Gómez-Moñivas S, Colchero J, Rodríguez-Peña M, Yang S, Zhao X, Lu YH, Chintala R, Reñones P, Altoe V, Martínez L, Huttel Y, Kawasaki S, Weber-Bargioni A, de la Peña ÓShea VA, Yang P, Ashby PD, Salmeron M. Photoinduced Charge Transfer and Trapping on Single Gold Metal Nanoparticles on TiO 2. ACS APPLIED MATERIALS & INTERFACES 2021; 13:50531-50538. [PMID: 34641675 PMCID: PMC8554764 DOI: 10.1021/acsami.1c13662] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 10/01/2021] [Indexed: 06/13/2023]
Abstract
We present a study of the effect of gold nanoparticles (Au NPs) on TiO2 on charge generation and trapping during illumination with photons of energy larger than the substrate band gap. We used a novel characterization technique, photoassisted Kelvin probe force microscopy, to study the process at the single Au NP level. We found that the photoinduced electron transfer from TiO2 to the Au NP increases logarithmically with light intensity due to the combined contribution of electron-hole pair generation in the space charge region in the TiO2-air interface and in the metal-semiconductor junction. Our measurements on single particles provide direct evidence for electron trapping that hinders electron-hole recombination, a key factor in the enhancement of photo(electro)catalytic activity.
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Affiliation(s)
- Monica Luna
- IMN-Instituto
de Micro y Nanotecnología (CNM-CSIC), 28760 Tres Cantos, Spain
| | - Mariam Barawi
- Photoactivated
Processes Unit, IMDEA-ENERGIA, 28935 Móstoles, Spain
| | - Sacha Gómez-Moñivas
- Departamento
de Ingeniería Informática, Escuela Politécnica
Superior, Universidad Autónoma de
Madrid, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Jaime Colchero
- Departamento
de Física, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain
| | | | - Shanshan Yang
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
| | - Xiao Zhao
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
| | - Yi-Hsien Lu
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
| | - Ravi Chintala
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
| | - Patricia Reñones
- Photoactivated
Processes Unit, IMDEA-ENERGIA, 28935 Móstoles, Spain
| | - Virginia Altoe
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
| | - Lidia Martínez
- Instituto
de Ciencia de Materiales de Madrid (ICMM-CSIC), 28049 Madrid, Spain
| | - Yves Huttel
- Instituto
de Ciencia de Materiales de Madrid (ICMM-CSIC), 28049 Madrid, Spain
| | - Seiji Kawasaki
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
| | - Alexander Weber-Bargioni
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
| | | | - Peidong Yang
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Paul D. Ashby
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
| | - Miquel Salmeron
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720 United States
- Materials
Science and Engineering Department, University
of California Berkeley, Berkeley, California 94720, United States
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4
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Pantle F, Becker F, Kraut M, Wörle S, Hoffmann T, Artmeier S, Stutzmann M. Selective area growth of GaN nanowires and nanofins by molecular beam epitaxy on heteroepitaxial diamond (001) substrates. NANOSCALE ADVANCES 2021; 3:3835-3845. [PMID: 36133019 PMCID: PMC9417268 DOI: 10.1039/d1na00221j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/04/2021] [Indexed: 05/12/2023]
Abstract
GaN-on-diamond is a promising route towards reliable high-power transistor devices with outstanding performances due to better heat management, replacing common GaN-on-SiC technologies. Nevertheless, the implementation of GaN-on-diamond remains challenging. In this work, the selective area growth of GaN nanostructures on cost-efficient, large-scale available heteroepitaxial diamond (001) substrates by means of plasma-assisted molecular beam epitaxy is investigated. Additionally, we discuss the influence of an AlN buffer on the morphology of the GaN nanostructures. The nanowires and nanofins are characterized by a very high selectivity and controllable dimensions. Low temperature photoluminescence measurements are used to evaluate their structural quality. The growth of two GaN crystal domains, which are in-plane rotated against each other by 30°, is observed. The favoring of a certain domain is determined by the off-cut direction of the diamond substrates. By X-ray diffraction we show that the GaN nanostructures grow perpendicular to the diamond surface on off-cut diamond (001) substrates, which is in contrast to the growth on diamond (111), where the nanostructures are aligned with the substrate lattice. Polarity-selective wet chemical etching and Kelvin probe force microscopy reveal that the GaN nanostructures grow solely in the Ga-polar direction. This is a major advantage compared to the growth on diamond (111) and enables the application of GaN nanostructures on cost-efficient diamond for high-power/high-frequency applications.
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Affiliation(s)
- Florian Pantle
- Walter Schottky Institut and Physics Department, Technische Universität München Am Coulombwall 4 85748 Garching Germany
| | - Fabian Becker
- Walter Schottky Institut and Physics Department, Technische Universität München Am Coulombwall 4 85748 Garching Germany
| | - Max Kraut
- Walter Schottky Institut and Physics Department, Technische Universität München Am Coulombwall 4 85748 Garching Germany
| | - Simon Wörle
- Walter Schottky Institut and Physics Department, Technische Universität München Am Coulombwall 4 85748 Garching Germany
| | - Theresa Hoffmann
- Walter Schottky Institut and Physics Department, Technische Universität München Am Coulombwall 4 85748 Garching Germany
| | - Sabrina Artmeier
- Walter Schottky Institut and Physics Department, Technische Universität München Am Coulombwall 4 85748 Garching Germany
| | - Martin Stutzmann
- Walter Schottky Institut and Physics Department, Technische Universität München Am Coulombwall 4 85748 Garching Germany
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5
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Daudin B, Donatini F, Bougerol C, Gayral B, Bellet-Amalric E, Vermeersch R, Feldberg N, Rouvière JL, Recio Carretero MJ, Garro N, Garcia-Orrit S, Cros A. Growth of zinc-blende GaN on muscovite mica by molecular beam epitaxy. NANOTECHNOLOGY 2021; 32:025601. [PMID: 32906087 DOI: 10.1088/1361-6528/abb6a5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The mechanisms of plasma-assisted molecular beam epitaxial growth of GaN on muscovite mica were investigated. Using a battery of techniques, including scanning and transmission electron microscopy, atomic force microscopy, cathodoluminescence, Raman spectroscopy and x-ray diffraction, it was possible to establish that, in spite of the lattice symmetry mismatch, GaN grows in epitaxial relationship with mica, with the [11-20] GaN direction parallel to [010] direction of mica. GaN layers could be easily detached from the substrate via the delamination of the upper layers of the mica itself, discarding the hypothesis of a van der Waals growth mode. Mixture of wurtzite (hexagonal) and zinc blende (ZB) (cubic) crystallographic phases was found in the GaN layers with ratios highly dependent on the growth conditions. Interestingly, almost pure ZB GaN epitaxial layers could be obtained at high growth temperature, suggesting the existence of a specific GaN nucleation mechanism on mica and opening a new way to the growth of the thermodynamically less stable ZB GaN phase.
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Affiliation(s)
- Bruno Daudin
- Univ. Grenoble-Alpes, CEA-IRIG, PHELIQS, 17 av. des Martyrs, 38000, Grenoble, France
| | - Fabrice Donatini
- Univ. Grenoble-Alpes, CNRS-Institut Néel, 25 av. des Martyrs, 38000, Grenoble, France
| | - Catherine Bougerol
- Univ. Grenoble-Alpes, CNRS-Institut Néel, 25 av. des Martyrs, 38000, Grenoble, France
| | - Bruno Gayral
- Univ. Grenoble-Alpes, CEA-IRIG, PHELIQS, 17 av. des Martyrs, 38000, Grenoble, France
| | - Edith Bellet-Amalric
- Univ. Grenoble-Alpes, CEA-IRIG, PHELIQS, 17 av. des Martyrs, 38000, Grenoble, France
| | - Rémy Vermeersch
- Univ. Grenoble-Alpes, CEA-IRIG, PHELIQS, 17 av. des Martyrs, 38000, Grenoble, France
| | - Nathaniel Feldberg
- Univ. Grenoble-Alpes, CEA-IRIG, PHELIQS, 17 av. des Martyrs, 38000, Grenoble, France
| | - Jean-Luc Rouvière
- Univ. Grenoble-Alpes, CEA-IRIG, MEM, 17 av. des Martyrs, 38000, Grenoble, France
| | | | - Núria Garro
- Institute of Materials Science (ICMUV), Universidad de Valencia, 22085, Valencia, Spain
| | - Saül Garcia-Orrit
- Institute of Materials Science (ICMUV), Universidad de Valencia, 22085, Valencia, Spain
| | - Ana Cros
- Institute of Materials Science (ICMUV), Universidad de Valencia, 22085, Valencia, Spain
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6
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Influence of Growth Polarity Switching on the Optical and Electrical Properties of GaN/AlGaN Nanowire LEDs. ELECTRONICS 2020. [DOI: 10.3390/electronics10010045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
For the development and application of GaN-based nanowire structures, it is crucial to understand their fundamental properties. In this work, we provide the nano-scale correlation of the morphological, electrical, and optical properties of GaN/AlGaN nanowire light emitting diodes (LEDs), observed using a combination of spatially and spectrally resolved cathodoluminescence spectroscopy and imaging, electron beam-induced current microscopy, the nano-probe technique, and scanning electron microscopy. To complement the results, the photo- and electro-luminescence were also studied. The interpretation of the experimental data was supported by the results of numerical simulations of the electronic band structure. We characterized two types of nanowire LEDs grown in one process, which exhibit top facets of different shapes and, as we proved, have opposite growth polarities. We show that switching the polarity of nanowires (NWs) from the N- to Ga-face has a significant impact on their optical and electrical properties. In particular, cathodoluminescence studies revealed quantum wells emissions at about 3.5 eV, which were much brighter in Ga-polar NWs than in N-polar NWs. Moreover, the electron beam-induced current mapping proved that the p–n junctions were not active in N-polar NWs. Our results clearly indicate that intentional polarity inversion between the n- and p-type parts of NWs is a potential path towards the development of efficient nanoLED NW structures.
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7
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Influence of Si Substrate Preparation Procedure on Polarity of Self-Assembled GaN Nanowires on Si(111): Kelvin Probe Force Microscopy Studies. ELECTRONICS 2020. [DOI: 10.3390/electronics9111904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The growth of GaN nanowires having a polar, wurtzite structure on nonpolar Si substrates raises the issue of GaN nanowire polarity. Depending on the growth procedure, coexistence of nanowires with different polarities inside one ensemble has been reported. Since polarity affects the optical and electronic properties of nanowires, reliable methods for its control are needed. In this work, we use Kelvin probe force microscopy to assess the polarity of GaN nanowires grown by plasma-assisted Molecular Beam Epitaxy on Si(111) substrates. We show that uniformity of the polarity of GaN nanowires critically depends on substrate processing prior to the growth. Nearly 18% of nanowires with reversed polarity (i.e., Ga-polar) were found on the HF-etched substrates with hydrogen surface passivation. Alternative Si substrate treatment steps (RCA etching, Ga-triggered deoxidation) were tested. However, the best results, i.e., purely N-polar ensemble of nanowires, were obtained on Si wafers thermally deoxidized in the growth chamber at ~1000 °C. Interestingly, no mixed polarity was found for GaN nanowires grown under similar conditions on Si(111) substrates with a thin AlOy buffer layer. Our results show that reversal of nanowires’ polarity can be prevented by growing them on a chemically uniform substrate surface, in our case on clean, in situ formed SiNx or ex situ deposited AlOy buffers.
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8
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Brubaker MD, Roshko A, Berweger S, Blanchard PT, Little CAE, Harvey TE, Sanford NA, Bertness KA. Crystallographic polarity measurements in two-terminal GaN nanowire devices by lateral piezoresponse force microscopy. NANOTECHNOLOGY 2020; 31:424002. [PMID: 32580185 DOI: 10.1088/1361-6528/ab9fb2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Lateral piezoresponse force microscopy (L-PFM) is demonstrated as a reliable method for determining the crystallographic polarity of individual, dispersed GaN nanowires that were functional components in electrical test structures. In contrast to PFM measurements of vertically oriented (as-grown) nanowires, where a biased probe tip couples to out-of-plane deformations through the d33 piezoelectic coefficient, the L-PFM measurements in this study were implemented on horizontally oriented nanowires that coupled to shear deformations through the d15 coefficient. L-PFM phase-polarity relationships were determined experimentally using a bulk m-plane GaN sample with a known [0001] direction and further indicated that the sign of the d15 piezoelectric coefficient was negative. L-PFM phase images successfully revealed the in-plane [0001] orientation of self-assembed GaN nanowires as part of a growth polarity study and results were validated against scanning transmission electron microscopy lattice images. Combined characterization of electrical properties and crystallographic polarity was also implemented for two-terminal GaN/Al0.1Ga0.9N/GaN nanowires devices, demonstrating L-PFM measurements as a viable tool for assessing correlations between device rectification and polarization-induced band bending.
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Affiliation(s)
- Matt D Brubaker
- Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO, United States of America
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9
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Yoon IT, Lee J, Tran NC, Yang W. Polarity Control of ZnO Films Grown on Ferroelectric (0001) LiNbO 3 Substrates without Buffer Layers by Pulsed-Laser Deposition. NANOMATERIALS 2020; 10:nano10020380. [PMID: 32098379 PMCID: PMC7075319 DOI: 10.3390/nano10020380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 11/25/2022]
Abstract
For this study, polarity-controlled ZnO films were grown on lithium niobate (LiNbO3) substrates without buffer layers using the pulsed-laser deposition technique. The interfacial structure between the ZnO films and the LiNbO3 was inspected using high-resolution transmission electron microscopy (HR-TEM) measurements, and X-ray diffraction (XRD) measurements were performed to support these HR-TEM results. The polarity determination of the ZnO films was investigated using piezoresponse force microscopy (PFM) and a chemical-etching analysis. It was verified from the PFM and chemical-etching analyses that the ZnO film grown on the (+z) LiNbO3 was Zn-polar ZnO, while the O-polar ZnO occurred on the (-z) LiNbO3. Further, a possible mechanism of the interfacial atomic configuration between the ZnO on the (+z) LiNbO3 and that on the (-z) LiNbO3 was suggested. It appears that the electrostatic stability at the substrate surface determines the initial nucleation of the ZnO films, leading to the different polarities in the ZnO systems.
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Affiliation(s)
- Im Taek Yoon
- Quantum Functional Semiconductor Research Center (QSRC), Dongguk University, 26 Phildong 3ga, Chung gu, Seoul 100-715, Korea;
| | - Juwon Lee
- Quantum Functional Semiconductor Research Center (QSRC), Dongguk University, 26 Phildong 3ga, Chung gu, Seoul 100-715, Korea;
- Correspondence: (J.L.); (W.Y.)
| | - Ngoc Cuong Tran
- Department of Physics, Dongguk University, 26 Phildong 3ga, Chung gu, Seoul 100-715, Korea;
| | - Woochul Yang
- Department of Physics, Dongguk University, 26 Phildong 3ga, Chung gu, Seoul 100-715, Korea;
- Correspondence: (J.L.); (W.Y.)
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10
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Feldberg N, Klymov O, Garro N, Cros A, Mollard N, Okuno H, Gruart M, Daudin B. Spontaneous intercalation of Ga and In bilayers during plasma-assisted molecular beam epitaxy growth of GaN on graphene on SiC. NANOTECHNOLOGY 2019; 30:375602. [PMID: 31151128 DOI: 10.1088/1361-6528/ab261f] [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
The formation of a self-limited metallic bilayer is reported during the growth of GaN by plasma-assisted molecular beam epitaxy on graphene on (0001) SiC. Depending on growth conditions, this layer may consist of either Ga or In, which gets intercalated between graphene and the SiC surface. Diffusion of metal atoms is eased by steps at SiC surface and N plasma induced defects in the graphene layer. Energetically favorable wetting of the (0001) SiC surface by Ga or In is tentatively assigned to the breaking of covalent bonds between (0001) SiC surface and carbon buffer layer. As a consequence, graphene doping and local strain/doping fluctuations decrease. Furthermore, the presence of a metallic layer below GaN opens the way to the development of devices with a spontaneously formed metallic electrode on their back side.
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Affiliation(s)
- Nathaniel Feldberg
- CEA, INAC-PHELIQS 'Nanophysics and semiconductors' group, F-38000 Grenoble, France. CEA, LETI, MINATEC campus, F-38000 Grenoble, France
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11
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Naresh-Kumar G, Bruckbauer J, Winkelmann A, Yu X, Hourahine B, Edwards PR, Wang T, Trager-Cowan C, Martin RW. Determining GaN Nanowire Polarity and its Influence on Light Emission in the Scanning Electron Microscope. NANO LETTERS 2019; 19:3863-3870. [PMID: 31035764 DOI: 10.1021/acs.nanolett.9b01054] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The crystal polarity of noncentrosymmetric wurtzite GaN nanowires is determined nondestructively in the scanning electron microscope using electron backscatter diffraction (EBSD). The impact of the nanowire polarity on light emission is then investigated using cathodoluminescence (CL) spectroscopy. EBSD can determine polarity of noncentrosymmetric crystals by interrogating differences in the intensity distribution of bands of the EBSD pattern associated with semipolar planes. Experimental EBSD patterns from an array of GaN nanowires are compared with theoretical patterns produced using dynamical electron simulations to reveal whether they are Ga- or N-polar or, as in several cases, of mixed polarity. CL spectroscopy demonstrates the effect of the polarity on light emission, with spectra obtained from nanowires of known polarity revealing a small but measurable shift (≈28 meV) in the GaN near band edge emission energy between those with Ga and N polarity. We attributed this energy shift to a difference in impurity incorporation in nanowires of different crystal polarity. This approach can be employed to nondestructively identify polarity in a wide range of noncentrosymmetric nanoscale material systems and provide direct comparison with their luminescence.
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Affiliation(s)
- G Naresh-Kumar
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - J Bruckbauer
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - A Winkelmann
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
- Laser Zentrum Hannover e.V. , 30419 Hannover , Germany
| | - X Yu
- Department of Electronic and Electrical Engineering , University of Sheffield , Sheffield S1 3JD , U.K
| | - B Hourahine
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - P R Edwards
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - T Wang
- Department of Electronic and Electrical Engineering , University of Sheffield , Sheffield S1 3JD , U.K
| | - C Trager-Cowan
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
| | - R W Martin
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , U.K
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Lacasa JS, Almonte L, Colchero J. In situ characterization of nanoscale contaminations adsorbed in air using atomic force microscopy. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:2925-2935. [PMID: 30546989 PMCID: PMC6278756 DOI: 10.3762/bjnano.9.271] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 11/01/2018] [Indexed: 05/31/2023]
Abstract
Under ambient conditions, surfaces are rapidly modified and contaminated by absorbance of molecules and a variety of nanoparticles that drastically change their chemical and physical properties. The atomic force microscope tip-sample system can be considered a model system for investigating a variety of nanoscale phenomena. In the present work we use atomic force microscopy to directly image nanoscale contamination on surfaces, and to characterize this contamination by using multidimensional spectroscopy techniques. By acquisition of spectroscopy data as a function of tip-sample voltage and tip-sample distance, we are able to determine the contact potential, the Hamaker constant and the effective thickness of the dielectric layer within the tip-sample system. All these properties depend strongly on the contamination within the tip-sample system. We propose to access the state of contamination of real surfaces under ambient conditions using advanced atomic force microscopy techniques.
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Affiliation(s)
- Jesús S Lacasa
- Centro de Investigación en Óptica y Nanofísica (CIOyN), Departamento Física, Facultad de Química, Campus Espinardo, Universidad de Murcia, 30100 Murcia, Spain
| | - Lisa Almonte
- Centro de Investigación en Óptica y Nanofísica (CIOyN), Departamento Física, Facultad de Química, Campus Espinardo, Universidad de Murcia, 30100 Murcia, Spain
- Electrical Engineering and Biological Science, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Jaime Colchero
- Centro de Investigación en Óptica y Nanofísica (CIOyN), Departamento Física, Facultad de Química, Campus Espinardo, Universidad de Murcia, 30100 Murcia, Spain
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Hetzl M, Kraut M, Hoffmann T, Stutzmann M. Polarity Control of Heteroepitaxial GaN Nanowires on Diamond. NANO LETTERS 2017; 17:3582-3590. [PMID: 28535070 DOI: 10.1021/acs.nanolett.7b00741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Group III-nitride materials such as GaN nanowires are characterized by a spontaneous polarization within the crystal. The sign of the resulting sheet charge at the top and bottom facet of a GaN nanowire is determined by the orientation of the wurtzite bilayer of the different atomic species, called N and Ga polarity. We investigate the polarity distribution of heteroepitaxial GaN nanowires on different substrates and demonstrate polarity control of GaN nanowires on diamond. Kelvin Probe Force Microscopy is used to determine the polarity of individual selective area-grown and self-assembled nanowires over a large scale. At standard growth conditions, mixed polarity occurs for selective GaN nanowires on various substrates, namely on silicon, on sapphire and on diamond. To obtain control over the growth orientation on diamond, the substrate surface is modified by nitrogen and oxygen plasma exposure prior to growth, and the growth parameters are adjusted simultaneously. We find that the surface chemistry and the substrate temperature are the decisive factors for obtaining control of up to 93% for both polarity types, whereas the growth mode, namely selective area or self-assembled growth, does not influence the polarity distribution significantly. The experimental results are discussed by a model based on the interfacial bonds between the GaN nanowires, the termination layer, and the substrate.
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Affiliation(s)
- Martin Hetzl
- Walter Schottky Institut and Physics Department, Technische Universität München , 85748 Garching, Germany
| | - Max Kraut
- Walter Schottky Institut and Physics Department, Technische Universität München , 85748 Garching, Germany
| | - Theresa Hoffmann
- Walter Schottky Institut and Physics Department, Technische Universität München , 85748 Garching, Germany
| | - Martin Stutzmann
- Walter Schottky Institut and Physics Department, Technische Universität München , 85748 Garching, Germany
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Zhang X, Haas B, Rouvière JL, Robin E, Daudin B. Growth mechanism of InGaN nano-umbrellas. NANOTECHNOLOGY 2016; 27:455603. [PMID: 27727147 DOI: 10.1088/0957-4484/27/45/455603] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
It is demonstrated that growing InGaN nanowires in metal-rich conditions on top of GaN nanowires results in a widening of the InGaN section. It is shown that the widening is eased by stacking faults (SFs) formation, revealing facets favorable to In incorporation. It is furthermore put in evidence that partial dislocations terminating SFs efficiently contribute to elastic strain relaxation. Indium accumulation on top of the InGaN section is found to result in an axial growth rate decrease, which has been assigned to increased N-N recombination and subsequent effective nitrogen flux decrease, eventually leading to the formation of InGaN nano-umbrellas/nanoplatelets.
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Affiliation(s)
- Xin Zhang
- University Grenoble Alpes, F-38000 Grenoble, France. CEA, INAC-PHELIQS, 'Nanophysique et semiconducteurs' group, F-38000 Grenoble, France. ALEDIA, 17 rue des martyrs, Bât. M23, F-38054 Grenoble Cedex 9, France
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Zhang X, Lourenço-Martins H, Meuret S, Kociak M, Haas B, Rouvière JL, Jouneau PH, Bougerol C, Auzelle T, Jalabert D, Biquard X, Gayral B, Daudin B. InGaN nanowires with high InN molar fraction: growth, structural and optical properties. NANOTECHNOLOGY 2016; 27:195704. [PMID: 27041669 DOI: 10.1088/0957-4484/27/19/195704] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The structural and optical properties of axial GaN/InGaN/GaN nanowire heterostructures with high InN molar fractions grown by molecular beam epitaxy have been studied at the nanoscale by a combination of electron microscopy, extended x-ray absorption fine structure and nano-cathodoluminescence techniques. InN molar fractions up to 50% have been successfully incorporated without extended defects, as evidence of nanowire potentialities for practical device realisation in such a composition range. Taking advantage of the N-polarity of the self-nucleated GaN NWs grown by molecular beam epitaxy on Si(111), the N-polar InGaN stability temperature diagram has been experimentally determined and found to extend to a higher temperature than its metal-polar counterpart. Furthermore, annealing of GaN-capped InGaN NWs up to 800 °C has been found to result in a 20 times increase of photoluminescence intensity, which is assigned to point defect curing.
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Affiliation(s)
- Xin Zhang
- Univ. Grenoble Alpes, 38000 Grenoble, France. CEA, INAC-PHELIQS, 'Nanophysique et semiconducteurs' group, 38000 Grenoble, France. ALEDIA, 17 rue des martyrs, Bât. M23, 38054 Grenoble Cedex 9, France
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Zhong WW, Huang YF, Gan D, Xu JY, Li H, Wang G, Meng S, Chen XL. Wetting behavior of water on silicon carbide polar surfaces. Phys Chem Chem Phys 2016; 18:28033-28039. [DOI: 10.1039/c6cp04686j] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Technically important wide band-gap semiconductors such as GaN, AlN, ZnO and SiC are crystallized in polar structures.
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Affiliation(s)
- W. W. Zhong
- Beijing National Laboratory for Condensed Matter Physics
- Institute of Physics
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - Y. F. Huang
- Beijing National Laboratory for Condensed Matter Physics
- Institute of Physics
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - D. Gan
- Beijing National Laboratory for Condensed Matter Physics
- Institute of Physics
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - J. Y. Xu
- Beijing National Laboratory for Condensed Matter Physics
- Institute of Physics
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - H. Li
- Beijing National Laboratory for Condensed Matter Physics
- Institute of Physics
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - G. Wang
- Beijing National Laboratory for Condensed Matter Physics
- Institute of Physics
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - S. Meng
- Beijing National Laboratory for Condensed Matter Physics
- Institute of Physics
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - X. L. Chen
- Beijing National Laboratory for Condensed Matter Physics
- Institute of Physics
- Chinese Academy of Sciences
- Beijing 100190
- China
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