III-V compliant substrates implemented by nanocavities introduced by ion implantation

A concept for the implementation of a compliant substrate using a buried layer of nanocavities is presented. The purpose of this nanocavity layer is to mechanically decouple a thin substrate layer from the rest of the substrate in order to relax stress in mismatched epilayers. The nanocavities were created by helium implantation in $InP(001)$ followed by thermal annealing under a phosphorous rich atmosphere. Metalorganic vapor phase epitaxy of $InAsP∕InP$ heterostructures grown simultaneously on substrates with nanocavities and on conventional substrates were characterized by high-resolution x-ray diffraction, transmission electron microscopy, and optical absorption. It is found that strain relaxation is enhanced for heterostructures grown on substrates with nanocavities and that the dislocations propagate partly in the compliant layer instead of the epilayer. The critical thickness of heterostructures grown on conventional substrates is roughly double that of structures grown on substrates containing nanocavities.