High cubic phase purity of ELOG cubic GaN on [110] mask‐stripe‐patterned GaAs (001) substrates by MOVPE

Abstract

Epitaxial lateral overgrowth (ELOG) of c‐GaN films was attempted on the mask‐stripe‐patterned GaAs substrates by MOVPE. Growth features, crystal quality, and generation of hexagonal phase inclusion were investigated as a function of growth time as well as thickness. At a growth temperature of 900 °C and a fill factor of 0.8, smooth sidewalls and top surfaces continued for a longer growth time. This resulted in a large reduction of hexagonal phase inclusion, which was confirmed by X‐ray reciprocal space mapping. To quantify the amount of hexagonal phase inclusion in the ELOG c‐GaN films with large variation in thickness, the effects of GaN X‐ray absorption and of the diffraction geometry were investigated. An amount of hexagonal phase inclusion as low as 3.1% was achieved at a growth time of 30 min (3.5 μm). The amount was found to decrease from 55.5 to 3.1% and 21.1%, when the film thickness increased from 1.4 to 3.5 μm and 12.0 μm, respectively.