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 1.269 eV 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 approximate to 0.30 eV above the valence band and an electron capture process from near the conduction band into tile defect. The defect lev el 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 ra nge. We explain this surprising result using an intradefect emission p rocess. These results are consistent with a vacancy related defect lev el, possibly stemming from a gallium vacancy-silicon at gallium (secon d-nearest-neighbor) defect complex.