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Title: Effect of AlN buffer layer properties on the morphology and polarity of GaN nanowires grown by molecular beam epitaxy

Abstract

Low-temperature AlN buffer layers grown via plasma-assisted molecular beam epitaxy on Si (111) were found to significantly affect the subsequent growth morphology of GaN nanowires. The AlN buffer layers exhibited nanowire-like columnar protrusions, with their size, shape, and tilt determined by the AlN V/III flux ratio. GaN nanowires were frequently observed to adopt the structural characteristics of the underlying AlN columns, including the size and the degree of tilt. Piezoresponse force microscopy and polarity-sensitive etching indicate that the AlN films and the protruding columns have a mixed crystallographic polarity. Convergent beam electron diffraction indicates that GaN nanowires are Ga-polar, suggesting that Al-polar columns are nanowire nucleation sites for Ga-polar nanowires. GaN nanowires of low density could be grown on AlN buffers that were predominantly N-polar with isolated Al-polar columns, indicating a high growth rate for Ga-polar nanowires and suppressed growth of N-polar nanowires under typical growth conditions. AlN buffer layers grown under slightly N-rich conditions (V/III flux ratio = 1.0 to 1.3) were found to provide a favorable growth surface for low-density, coalescence-free nanowires.

Authors:
 [1]; ;  [2]; ; ;  [1];  [3]
  1. Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)
  2. Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
  3. Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States)
Publication Date:
OSTI Identifier:
22038689
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 110; Journal Issue: 5; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; ALUMINIUM NITRIDES; COALESCENCE; CRYSTAL GROWTH; ELECTRON BEAMS; ELECTRON DIFFRACTION; GALLIUM NITRIDES; LAYERS; MICROSCOPY; MOLECULAR BEAM EPITAXY; MORPHOLOGY; NUCLEATION; PLASMA; QUANTUM WIRES; SEMICONDUCTOR MATERIALS; SURFACES

Citation Formats

Brubaker, Matt D, Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, DARPA Center for Integrated Micro/Nano-Electromechanical Transducers, Levin, Igor, Davydov, Albert V, Rourke, Devin M, Sanford, Norman A, Bertness, Kris A, Bright, Victor M, and DARPA Center for Integrated Micro/Nano-Electromechanical Transducers. Effect of AlN buffer layer properties on the morphology and polarity of GaN nanowires grown by molecular beam epitaxy. United States: N. p., 2011. Web. doi:10.1063/1.3633522.
Brubaker, Matt D, Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, DARPA Center for Integrated Micro/Nano-Electromechanical Transducers, Levin, Igor, Davydov, Albert V, Rourke, Devin M, Sanford, Norman A, Bertness, Kris A, Bright, Victor M, & DARPA Center for Integrated Micro/Nano-Electromechanical Transducers. Effect of AlN buffer layer properties on the morphology and polarity of GaN nanowires grown by molecular beam epitaxy. United States. https://doi.org/10.1063/1.3633522
Brubaker, Matt D, Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, DARPA Center for Integrated Micro/Nano-Electromechanical Transducers, Levin, Igor, Davydov, Albert V, Rourke, Devin M, Sanford, Norman A, Bertness, Kris A, Bright, Victor M, and DARPA Center for Integrated Micro/Nano-Electromechanical Transducers. 2011. "Effect of AlN buffer layer properties on the morphology and polarity of GaN nanowires grown by molecular beam epitaxy". United States. https://doi.org/10.1063/1.3633522.
@article{osti_22038689,
title = {Effect of AlN buffer layer properties on the morphology and polarity of GaN nanowires grown by molecular beam epitaxy},
author = {Brubaker, Matt D and Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 and DARPA Center for Integrated Micro/Nano-Electromechanical Transducers and Levin, Igor and Davydov, Albert V and Rourke, Devin M and Sanford, Norman A and Bertness, Kris A and Bright, Victor M and DARPA Center for Integrated Micro/Nano-Electromechanical Transducers},
abstractNote = {Low-temperature AlN buffer layers grown via plasma-assisted molecular beam epitaxy on Si (111) were found to significantly affect the subsequent growth morphology of GaN nanowires. The AlN buffer layers exhibited nanowire-like columnar protrusions, with their size, shape, and tilt determined by the AlN V/III flux ratio. GaN nanowires were frequently observed to adopt the structural characteristics of the underlying AlN columns, including the size and the degree of tilt. Piezoresponse force microscopy and polarity-sensitive etching indicate that the AlN films and the protruding columns have a mixed crystallographic polarity. Convergent beam electron diffraction indicates that GaN nanowires are Ga-polar, suggesting that Al-polar columns are nanowire nucleation sites for Ga-polar nanowires. GaN nanowires of low density could be grown on AlN buffers that were predominantly N-polar with isolated Al-polar columns, indicating a high growth rate for Ga-polar nanowires and suppressed growth of N-polar nanowires under typical growth conditions. AlN buffer layers grown under slightly N-rich conditions (V/III flux ratio = 1.0 to 1.3) were found to provide a favorable growth surface for low-density, coalescence-free nanowires.},
doi = {10.1063/1.3633522},
url = {https://www.osti.gov/biblio/22038689}, journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 5,
volume = 110,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 2011},
month = {Thu Sep 01 00:00:00 EDT 2011}
}