Comparative study of photoluminescence in ordered and disordered Ga0.5In0.5P alloys under hydrostatic pressure

摘要

We have measured the photoluminescence (PL) spectra of ordered GaInP alloys grown by organometallic vapor phase epitaxy (OMVPE) at three different growth temperatures (Tg =600, 650, and 700°C) as a function of pressure up to about 4.0 GPa at a temperature of 300 K. We have also done similar measurements on a disordered (bulk) alloy for comparison. We find that the band-gap energy Eo, derived from the PL peak spectra, of ordered alloys shows a sublinear pressure dependence and is significantly different from that of the disordered sample. The overall shift of Eo with pressure up to 3.5 GPa for the ordered sample grown at 700°C is smaller than for both the ordered material grown at 600°C and the disordered sample studied. The observed behavior of E can be related to the existence of a CuPt-type ordered structure in which the degree of ordering depends on Tg and the repulsion between Gamma-folded states affects the band-gap energy.