Freestanding-quality dislocation density in semipolar GaN epilayers grown on SOI: aspect ratio trapping

摘要

We demonstrate that the aspect ratio trapping technique, aimed at blocking threading dislocations and implemented for cubic materials, can also be used for hexagonal symmetry materials such as GaN. We used patterned (001) 6 degrees off silicon on insulator substrates to grow semipolar (10-11) GaN layers on nanometric (111) Si facets, with a 550 nm SiO2 blocking mask. The dislocations coming from the inclined growth facet are shown to bend in the c-plane and trapped on the sidewall of the mask. The semipolar GaN layers have dislocation densities smaller than 10(7) cm(-2), mimicking the dislocation density of commercial c-oriented GaN freestanding substrates.