Effects of sub-gap irradiation on the time-of-flight current waveforms of high resistivity CdTe

Effects of IR irradiation on TOF current waveforms of a CdTe:Cl crystal with Pt electrodes on its (111) faces have been investigated. An increase of TOF current and a change in the evolution of DC photocurrent versus applied voltage by IR irradiation are observed. By taking into account an effect of surface recombination, satisfactory fits to theory are obtained for the charge collection efficiency and the DC photocurrent versus applied voltage. These results show that the observed effects are mainly explained by a reduction of surface recombination velocity rather than by an increase of bulk carrier lifetime. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)