Growth of GaN on Patterned Sapphire Substrate with High-Index Facets

Abstract

Periodic pyramidal array patterned sapphire substrate (PSS) with various inclined facets was fabricated by wet etching. It was found that {3 (4) over bar 17}, {4 (1) over bar(3) over bar 18}, and {12 (3) over bar5} facets are exposed on the PSS structure after etching. GaN grown on the PSS by metal-organic chemical vapor deposition was found to have a semi-polar orientation by structural characterization with scanning and transmission electron microscopy. Also, the results show that GaN is mainly grown on the {12 (3) over bar5} sapphire facet with the orientation relationship between GaN and sapphire as(01 (1) over bar(4) over bar)(GaN) // (3 (3) over bar0 (6) over bar)(sapphire) and [02 (2) over bar1](GaN) // [11 (2) over bar0](sapphire), and the dislocation density in the grown GaN decreased with thickness. In addition, photoluminescence and catholuminescence measurements show only strong near-band-edge emission from the semi-polar GaN on the {12 (3) over bar5} sapphire facet. (C) 2015 The Electrochemical Society. All rights reserved.