It was demonstrated that positron annihilation provided a direct method for separating vacancy-type and ion-type acceptors in p-type Hg0.78Cd0.22Te crystals. It was shown that positron and Hall effect data could be combined in order to deduce the concentrations of acceptors of both types, and donors. In the case of crystals with a low concentration of negative ions, there was clear evidence that the vacancies had 2 ionization levels: 2-  1- and 1-  0.

L.Baroux, C.Corbel, F.M.Kiessling, S.Rolland, R.Granger, W.Hoerstel, R.Triboulet: Physical Review Letters, 1995, 75[3], 557-60