Pressure studies of resonant DX centers: Thermal emission from metastable Si and S donors in GaAs

The analysis of the process of establishing a thermal equilibrium in a GaAs sample, in which the metastable state was created by high pressure freeze-out, makes possible a determination of the energy barrier for emission from resonant DX centers. We have found that Si and S centers exhibit qualitatively different pressure behavior. This result casts doubt on some models describing DX center.