A study of GaN regrowth on the micro‐facetted GaN template formed by in‐situ thermal etching

Abstract

AbstractWe report a study of GaN regrowth on micro‐facetted GaN templates formed by in‐situ thermal etching in a low‐pressure metalorganic chemical vapor deposition system. First, the 1.5 µm‐thick GaN epilayers were grown on c‐plane sapphire substrates. This was followed by an in‐situ thermal etching process under hydrogen and ammonia ambient with the etching time being a parameter. The thermally etched GaN templates showed hexagonal GaN pyramids, which were aligned along the growth direction on the c‐plane substrate. The 3 µm‐thick GaN regrowth was performed on these micro‐facetted GaN templates. The surface of the overgrown GaN was atomically smooth. The full width at half maximum of (102) peak in the X‐ray rocking curve profile decreased from 9.5 to 6.5 arcmin as the thermal etching time increased from 0 to 45 min. Etch pit density measurements revealed that the pit density of regrown GaN decreased by about one order of magnitude, compared to that of the control sample. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)