PHOTOLUMINESCENCE OF ZINCBLENDE GAN UNDER HYDROSTATIC-PRESSURE

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