The defects, in p-type material, which existed after annealing under Te vapor were studied using capacitance deep-level transient spectroscopy. The main defect was associated with 2 deep-level transient spectroscopy lines with activation energies of 0.20 and 0.23eV. The ratio of their amplitudes depended upon the filling pulse length. By assuming that the defect could capture 2 holes, a model was proposed which explained the unusual properties of the defect. The capture of the second hole was associated with a large lattice relaxation and was thermally activated to such an extent that an inverted ordering of the thermal activation enthalpies was observed. From the electric field dependence of the hole emission rates, it was deduced that one level had a donor nature while the other had an acceptor nature. The dependence of the defect concentration upon the annealing temperature indicated that the defect was probably a Cd-vacancy complex.

G.Zoth, W.Schröter: Philosophical Magazine B, 1988, 58[6], 623-33