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Title: Transport and optical properties of c-axis oriented wedge shaped GaN nanowall network grown by molecular beam epitaxy

The transport and optical properties of wedge-shaped nanowall network of GaN grown spontaneously on cplane sapphire substrate by Plasma-Assisted Molecular Beam Epitaxy (PAMBE) show interesting behavior. The electron mobility at room temperature in these samples is found to be orders of magnitude higher than that of a continuous film. Our study reveals a strong correlation between the mobility and the band gap in these nanowall network samples. However, it is seen that when the thickness of the tips of the walls increases to an extent such that more than 70% of the film area is covered, it behaves close to a flat sample. In the sample with lower surface coverage (≈40% and ≈60%), it was observed that the conductivity, mobility as well as the band gap increase with the decrease in the average tip width of the walls. Photoluminescence (PL) experiments show a strong and broad band edge emission with a large (as high as ≈ 90 meV) blue shift, compared to that of a continuous film, suggesting a confinement of carriers on the top edges of the nanowalls. The PL peak width remains wide at all temperatures suggesting the existence of a high density of tail states at themore » band edge, which is further supported by the photoconductivity result. The high conductivity and mobility observed in these samples is believed to be due to a “dissipation less” transport of carriers, which are localized at the top edges (edge states) of the nanowalls.« less
Authors:
;  [1] ; ; ;  [2]
  1. Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra-400076 (India)
  2. Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Bangalore- 560064 (India)
Publication Date:
OSTI Identifier:
22264086
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1583; Journal Issue: 1; Conference: ICDS-2013: 27. international conference on defects in semiconductors, Bologna (Italy), 21-26 Jul 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DENSITY; ELECTRON MOBILITY; FILMS; GALLIUM NITRIDES; MOLECULAR BEAM EPITAXY; OPTICAL PROPERTIES; PEAKS; PHOTOCONDUCTIVITY; PHOTOLUMINESCENCE; PLASMA; SAPPHIRE; SUBSTRATES; THICKNESS