Thermally-Stimulated Current in p-Type CdTe Annealed in Various Atmospheres

The thermally-stimulated currents were measured in the space-charge region of a Schottky diode formed on as-grown or annealed p-type CdTe. The as-grown samples were annealed at temperatures from 200–600°C for 300 min in Cd or Te vapor. Four traps, all of which have been previously reported in the literature, were found in as-grown CdTe at 0.24, 0.40, 0.48 and 0.53 eV above the valence band. Four new traps at 0.053, 0.11, 0.15 and 0.18 eV above the valence band were found in p-type CdTe annealed in Te vapor, and two traps with energies of E v+0.098 and E v+0.28 eV were found in p-type CdTe annealed in Cd vapor. It was evident from TSC measurements combined with the removal of a very thin film that the traps found in the annealed samples are localized near the surface.