Cryogenic pressure and lifetime studies of a defect related emission in heavily silicon doped GaAs

We have used cryogenic high pressure measurements and lifetime studies to investigate a defect related emission at 1.269eV in silicon doped GaAs. The pressure measurements prove that the 1.269 eV photon energy is relative to the conduction band. This implies a deep defect level ≈ 0.30 eV above the valence band and an electron capture process from near the conduction band into the defect. The defect level moves up in the bandgap at a rate of (23 ± 3) meV/GPa. Between 20 K and room temperature the defect emission lifetime remains constant at (9.63 ± 0.25) ns, while the intensity decreases over this same range. We explain this surprising result using an intradefect emission process. These results are consistent with a vacancy related defect level, possibly stemming from a gallium vacancy - silicon at gallium (second-nearest-neighbor) defect complex.