Growth and optical properties of natural InAs1−x Sb x strained layer superlattices

MBE growlh of InAs_1−xSb_x below 430°C results in its coherent phase separation into tetragonally distorted platelets of two different compositions, that is the formation of a ‘natural’ strained layer superlatticc (n-SLS). The results presented here suggest that the n-SLS is generated at or near to the growth front by a process of surface diffusion. A similar behaviour in GaAs_1−xSb_x suggests that it may be associated with a possible miscibility gap in the As-Sb phase diagram rather than that of the ternary alloy. A comparison of the optical properties of n-SLS with those of conventionally grown SLSs is made.