Spectroscopic study of self-organized quantum dot like structures in Ga-In-P superlattices on (311) GaAs

We report temperature dependent photoluminescence, contactless electrorefle ctance and photoluminescence excitation study of (GaP)(2) (InP)(2.5) strain ed short period superlattices sandwiched between GaxIn1-xP alloy layers gro wn on GaAs (311)A substrates. Transmission electron microscope pictures of these samples reveal the presence of self-organized In rich globular struct ures with Ga rich surroundings in the superlattice planes. The variation of the peak position of the photoluminescence band with decreasing temperatur e has an anomalous dip. We show that this is not due to an anomalous change in the band gap with temperature but is due to the interplay between two l uminescence pathways associated with two phases, one which has the original (GaP)(2) (InP)(2.5) superlattice and the other being the self-organized co mposition modulated In rich regions within the superlattice layers. We also present spectroscopic results which indicate quantum dot like nature of th e self-organized In rich structures in these samples. (C) 1999 American Ins titute of Physics. [S0021-8979(99)03905-5].