Abstract
We have studied the defects in p-type CdTe after annealing under Te-vapour pressure by capacitance deep-level transient spectroscopy (DLTS). The major defect is associated with two DLTS lines with activation enthalpies of 0·20 and 0·23 eV. The ratio of their amplitudes depends on the filling pulse length and for the maximum amplitudes is two. Assuming that the defect can capture two holes, we propose a model that explains the unusual properties of this defect: the capture of the second hole is associated with a large lattice relaxation and thermally activated to such an extent that an inverted ordering of the thermal activation enthalpies is observed. From the electric field dependence of the hole emission rates we infer for one level a donor character and for the other level an acceptor character. The dependence of the defect concentration on the annealing temperature indicates that the defect is probably a Cd-vacancy complex.