BAND-GAP LEVEL OF THE CADMIUM VACANCY IN CDTE

The reaction A(gCd) --> A(gi) + V-Cd was used to create cadmium vacanc ies V-Cd in the space charge region of a Schottky contact on p-type Cd Te. At T = 380 K, the A(gi)(+) ions were drifted out of the space char ge region by the high electric field under reverse bias condition. Aft er cooling down to 80 K with applied reverse bias, admittance spectros copy measurements were performed. Only after this reverse bias anneali ng, an additional defect with a thermal activation energy of E-v + 0.2 3(3) eV is observed. In other samples, the existence of V-Cd after sil ver diffusion was monitored by perturbed angular correlation spectrosc opy (PAC). Here, admittance spectroscopy reveals the same activation e nergy of the electrically dominating defects as given above. This resu lt supports the assignment of this level to cadmium vacancy accepters. (C) 1998 Elsevier Science B.V. All rights reserved.