Preventing phase separation in MOCVD-grown InAlAs compositionally graded buffer on silicon substrate using InGaAs interlayers

Abstract

Compositionally graded InAlAs buffers grown by metal–organic chemical vapor deposition are impaired by phase separation occurring at In content higher than 35%. Phase separation results in rough epilayers with poor crystalline material quality. By introducing low temperature grown InGaAs interlayers in the compositionally graded InAlAs buffer, the surface roughness decreases, allowing a grading of up to In0.60Al0.40As without any phase separation occurring. This composite buffer is applied to fabricate a 200mm diameter InP-on-Si virtual substrate with a threading dislocation density around 1×108cm−2.