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Structure and strain relaxation effects of defects in InxGa1-xN epilayers


Type

Article

Change log

Authors

Rhode, SL 
Fu, WY 
Moram, MA 
Massabuau, FCP 
Kappers, MJ 

Abstract

jats:pThe formation of trench defects is observed in 160 nm-thick InxGa1−xN 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.</jats:p>

Description

Keywords

40 Engineering, 4016 Materials Engineering, 51 Physical Sciences, 5104 Condensed Matter Physics

Journal Title

Journal of Applied Physics

Conference Name

Journal ISSN

0021-8979
1089-7550

Volume Title

116

Publisher

AIP Publishing
Sponsorship
Engineering and Physical Sciences Research Council (EP/H019324/1)
Engineering and Physical Sciences Research Council (EP/I012591/1)
This work was funded in part by the Cambridge Commonwealth trust and the EPSRC. SKR is funded through the Cambridge-India Partnership Fund and Indian Institute of Technology Bombay via a scholarship. SKR also acknowledges funds from St. John’s College. MAM acknowledges support from the Royal Society through a University Research Fellowship.