Defects in cadmium selenide

Abstract

Deep levels in undoped and copper doped CdSe have been investigated using a variety of depletion region capacitance and photoconductivity techniques. A photoconductivity sensitising centre with a level 0.62 eV above the valence band was found in undoped material. This level was also detected in copper doped CdSe, but the main copper centre was associated with a level ∼ 1.0 eV above the valence band. The hole capture cross section for this centre was ∼ 10 -13 cm 2 (from ODLTS) and its electron capture cross-section was ∼ 10 -18 cm 2 (from DLTS). The cross-section ratio of ∼ 10 5 clearly indicates that the copper centre also acts as a photoconductivity sensitiser.