Defect reduction in non‐polar (11$ \bar 2 $0) GaN grown on (1$ \bar 1 $02) sapphire

Abstract

AbstractThis work assesses the relative effectiveness of different techniques to reduce defect density in heteroepitaxial, non‐polar, a ‐plane GaN films grown on r ‐plane sapphire by MOVPE. Plan view TEM was used to obtain the defect density of films grown by different methods. The as‐grown material was found to have a high dislocation and basal plane stacking fault (BSF) density (1.9 (± 0.2) × 1011 cm–2 and 1.1 (± 0.9) × 106 cm–1 respectively). The four defect reduction techniques tested were: 3D–2D growth, SiNx interlayers, ScN interlayers and epitaxial lateral overgrowth (ELOG). Both dislocation and BSF density were reduced by all methods compared to the as‐grown material. The lowest defect density was achieved in the (0001) wing of the ELOG sample and was <1 × 106 dislocations cm–2 and 2.0 (± 0.7) × 104 BSFs cm–1. On the wafer scale, ScN interlayers were most effective: A single 5 nm thick ScN interlayer reduced the BSF density to 5.9 (± 0.8) × 105 cm–1 and the dislocation density was reduced by two orders of magnitude to 1.8 (± 0.2) × 109 cm–2 compared to the as‐grown material. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)