Defect distribution in CdTe after Cd saturated annealing

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Abstract

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)

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