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

We report temperature dependent photoluminescence, contactless electroreflectance and photoluminescence excitation study of (GaP)(2) (InP)(2.5) strained short period superlattices sandwiched between GaxIn1-xP alloy layers grown on GaAs (311)A substrates. Transmission electron microscope pictures of these samples reveal the presence of self-organized In rich globular structures with Ga rich surroundings in the superlattice planes. The variation of the peak position of the photoluminescence band with decreasing temperature 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 luminescence pathways associated with two phases, one which has the original (GaP)(2) (InP)(2.5) superlattice and the other being the self-organized composition modulated In rich regions within the superlattice layers. We also present spectroscopic results which indicate quantum dot like nature of the self-organized In rich structures in these samples. (C) 1999 American Institute of Physics. [S0021-8979(99)03905-5].