Reduction of Planar Defect Density in Laterally Overgrown Cubic-GaN on Patterned GaAs(001) Substrates by MOVPE

Abstract

The metalorganic vapor phase epitaxy (MOVPE) growth of cubic-GaN (c-GaN) layers has been performed on the [110]-stripe patterned GaAs (001) substrates. The surface morphology of the laterally overgrown layer was much improved with the formation of the flat (311)A surfaces as the growth proceeded. It is shown that the c-GaN layer thicker than 20 μm was grown on GaAs(001) substrates with the stripe direction in [110] for 90 min. Microstructure and extended defect distribution in the laterally overgrown c-GaN films have been analysed by transmission electron microscopy (TEM). It is found that the planar defect (stacking faults and twins) density drastically decreases at the region away from the substrate toward the top of the c-GaN stripe. On the other hand, the dislocations become dominant. The density of the dislocations was found to be lower than 10 8 cm -2 . These results suggest that the lateral overgrowth on [110]-stripe-patterned GaAs (001) substrates via MOVPE is an efficient method for obtaining a low planar defect density c-GaN layer.