PRESSURE-INDUCED GAMMA-X CROSSOVER IN THE CONDUCTION-BAND OF ORDERED AND DISORDERED GAINP ALLOYS

Pressure-dependent photoluminescence in both ordered and disordered Ga 0.5In0.5P is reported. In ordered Ga0.5In0.5P, emissions are observed from both the direct band gap at the Brillouin zone center (GAMMA) and from the indirect band gap involving the conduction band at the X poi nt of the Brillouin zone. The conduction-band minima at X and GAMMA in the ordered phase are found to be lowered in energy by the same amoun t with respect to those in the disordered phase. Our results support t he existence of ordering along the [001] direction in GaInP as propose d recently by Kurtz.