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Title: Structure and strain relaxation effects of defects in In{sub x}Ga{sub 1–x}N epilayers

The formation of trench defects is observed in 160 nm-thick In{sub x}Ga{sub 1–x}N epilayers with x≤0.20, grown on GaN on (0001) sapphire substrates using metalorganic vapour phase epitaxy. The trench defect density increases with increasing indium content, and high resolution transmission electron microscopy shows an identical structure to those observed previously in InGaN quantum wells, comprising meandering stacking mismatch boundaries connected to an I₁-type basal plane stacking fault. These defects do not appear to relieve in-plane compressive strain. Other horizontal sub-interface defects are also observed within the GaN pseudosubstrate layer of these samples and are found to be pre-existing threading dislocations which form half-loops by bending into the basal plane, and not basal plane stacking faults, as previously reported by other groups. The origins of these defects are discussed and are likely to originate from a combination of the small in-plane misorientation of the sapphire substrate and the thermal mismatch strain between the GaN and InGaN layers grown at different temperatures.
Authors:
; ; ; ; ; ; ;  [1] ;  [1] ;  [2] ;  [3]
  1. Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)
  2. (United Kingdom)
  3. Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India)
Publication Date:
OSTI Identifier:
22305942
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTAL DEFECTS; DENSITY; DISLOCATIONS; GALLIUM COMPOUNDS; GALLIUM NITRIDES; INDIUM COMPOUNDS; INTERFACES; LAYERS; NITROGEN COMPOUNDS; QUANTUM WELLS; RELAXATION; RESOLUTION; SAPPHIRE; STACKING FAULTS; STRAINS; SUBSTRATES; TEMPERATURE DEPENDENCE; TRANSMISSION ELECTRON MICROSCOPY; VAPOR PHASE EPITAXY