PHOTOLUMINESCENCE OF ZINCBLENDE GAN UNDER HYDROSTATIC-PRESSURE

Photoluminescence spectra of cubic GaN grown on a GaAs substrate by mo lecular beam epitaxy have been studied as a function of hydrostatic pr essure at 10 K. The spectra are abundant in emission structures arisin g from a variety of radiative recombination processes, such as free-el ectron-bound-hole and donor-acceptor pair transitions. These emission peaks shift to higher energy with increasing pressure, providing a mea sure of the pressure coefficient of the band gap of cubic GaN. In addi tion, a spectral feature, which is superimposed on the other emission peaks and not observable at atmospheric pressure, becomes gradually re solvable as pressure increases. The difference of pressure dependence of this emission from the others suggests that it is associated with a deep center.