The electrical and optical properties of undoped CdTe after Cd saturated annealing were studied at 4.2 to 300K. It was observed that p-to-n conversion and anomalous n-to-p re-conversion occurred during annealing. The converted n-type was characterized by a slightly compensated donor level with an ionization energy, ED, of some 12 to 14meV and an electron mobility which attained 45000cm2/Vs at 25K. The compensation rate in the n-type layer decreased with annealing time; even approaching zero level after 27h of annealing at 600C. The p-to-n conversion was also confirmed by photoluminescence, where the intensity of the photoluminescence lines of the neutral acceptor bound excitons (A°,X) was significantly reduced and bound exciton-neutral donor (D°,X) and free excitons lines were intensified in the n-type layer, as compared with as-grown p-type samples. Anomalous n-to-p re-conversion of the converted n-type layer to p-type, with electrical properties which were quite different to as-grown p-type samples, occurred after 40h of annealing at 600C.

Defect Distribution in CdTe after Cd Saturated Annealing. E.Belas, R.Grill, P.Horodyský, P.Moravec, J.Franc, P.Höschl: Physica Status Solidi C, 2005, 2[3], 1155-60