Defect distribution in CdTe after Cd saturated annealing



The electrical and optical properties of undoped CdTe after Cd saturated annealing have been studied at the temperature interval 4.2–300 K. We observed that the p-to-n conversion and anomalous n-to-p reconversion occurs during annealing. The converted n-type is characterized by slightly compensated donor level with ionization energy ED ∼ 12–14 meV and the high electron mobility which reaches up to 45000 cm2/Vs at 25 K. The compensation rate in the n-type layer decreases with annealing time even to zero level after 27 hours annealing at 600 °C. P-to-n conversion was also confirmed by photoluminescence, where the intensity of the photoluminescence lines of the neutral acceptor bound excitons (A°,X) is significantly reduced and bound exciton-neutral donor (D°,X) and free excitons lines are intensified in the n-type layer comparing with as grown p-type samples. Anomalous n-to-p reconversion of the converted n-type layer to p-type with electrical properties quite different from as-grown p-type sample occurs after 40 hours annealing at 600 °C. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)