In situ and ex situ evaluation of mechanisms of lateral epitaxial overgrowth

Metal organic chemical vapour deposition was used for lateral epitaxial overgrowth of GaN on stripe-patterned SiO2 masks 200 and 500 nm in thickness. Overgrowths were conducted under constant conditions, at a nominal temperature of 1140 degreesC. Mechanistic aspects were investigated by a combination of ex situ imaging methods and in situ optical reflectometry. Short growth times resulted in non-coalesced GaN with horizontal (0001) and sloping [1122] side facets. but vertical [1120] facets completely replaced the [1122] facets before coalescence. Reflectance versus time plots from stripe-masked areas suggest an interplay of two distinct interference effects. These data indicate a constant vertical growth rate of approximate to2.6 mum/h after coalescence, and are consistent with enhancement in growth rate in the early stages. associated with transport of precursor species from SiO2 mask regions.