RADIATIVE RECOMBINATION OF MECHANICALLY DISORDERED UNDOPED P-TYPE CDTE

Radiative recombination of undoped p-type CdTe, disordered by grinding , at 4.2 and 77 K is investigated. It is shown that as the dislocation density increases from 5 x 10(3) up to 10(5) cm(-2), the intensities of the 1.475-eV (4.2 K) line and the band with a maximum at 1.0 eV (77 K) increase in the photoluminescence spectrum against a background of a general decrease in the intensities of the initially observed bands . The 1.475-eV line is due to recombination of an exciton, bound by th e potential of a complex defect, which possesses several configuration forms, and a band at 1.0 eV-direct recombination of an electron on ti le level of a defect and a hole from the valence band. The correlated increase in the intensities of the 1.474-eV line and the 1.0-eV band i s explained by tile fact that they are associated with the same defect , which possesses a donor level with energy depth E(c) - 0.64 eV. A te llurium cluster, incorporating several antistructural defects Te-Cd an d interstitial tellurium atoms, is proposed as a chemical model for th e defect. It is suggested that such a defect is also formed during the preparation of a metal-CdTe Schottky barrier, which gives rise to pin ning of the Fermi level at the level E(c)-0.64 eV. (C) 1996 American I nstitute of Physics.