Photoluminescence and photoconductivity in CdTe crystals doped with Bi

Defect levels in CdTe doped with Bi are studied by low temperature photoluminescence, photoinduced current transient spectroscopy, photoconductivity measurements, and optical absorption. Two centers associated with the doping with Bi are reported. The first one, a deep level located at Ev +0.71 eV, only present at low dopant concentrations, has donor character and hole-trap properties, and is mainly responsible for the high resistivity and very high photoconductivity of the samples. The second one, an acceptor center located at Ev +0.30 eV, assigned to BiTe species, is only present at high dopant concentrations and is mainly responsible for the low resistivity and poor photoconductivity of these samples.