Donor compensation by associates of donor impurities and cation vacancies was investigated in vapour-grown I-doped material and Al-diffused melt-grown bulk crystals. Both (ISeVZn) and (AlZnVZn) A-centres could be identified by using electron paramagnetic resonance spectroscopy. The concentrations of the compensating defects could be reversibly changed by vapour-phase equilibration, and a reproducible adjustment of the room-temperature carrier concentrations was possible. The results were explained in terms of a defect chemical model. The supposedly high concentration of one type of vacancy-associated defect was confirmed by using positron annihilation techniques.

Reversible Conductivity Control and Quantitative Identification of Compensating Defects in ZnSe Bulk Crystals. M.Prokesch, K.Irmscher, J.Gebauer, R.Krause-Rehberg: Journal of Crystal Growth, 2000, 214-215, 988-92