LUMINESCENCE OF NI2+ AND NI+ IONS IN ZNTE

Fine structures of the luminescence bands T-3(2)(F) --> T-3(1)(F) of N i2+ and E-2(D) --> T-2(2)(D) of Ni+ in ZnTe bulk crystals are presente d. A threefold split zero-phonon line near 3840 cm(-1) is assigned to Ni2+ and a main line at 3095 cm(-1) followed by a low-energy statellit e in a distance of 400 cm(-1) to Ni+. A comparison with other host cry stals reveals an almost linear dependence of the transition energies o n the band gap. Charge-transfer energies are deduced from excitation s pectra. (C) 1997 Elsevier Science Ltd.