Optical and theoretical investigations of V2+ ions in CdZnTe crystal

High-resistivity CdZnTe:V crystals are investigated by photoluminescence (PL) and by time-resolved PL in the infrared spectral range. A double peaked emission band is detected around 0.8 eV and it is related to vanadium doping. No-phonon lines of the internal transitions were detected. This emission is interpreted as a balance between the 4T1(4P)→4T1(4F) internal transition and an electronic transition from the conduction band to the 4T1(4F) ground state of V2+. The corresponding decay time after laser excitation gives evidence to the contribution of two different recombination processes. These two emission bands are separated by time-resolved luminescence. Crystal-field calculations of the detected transition energies based on Tanabe-Sugano scheme are presented and the Racah parameter B and crystal-field intensity Dq were determined. In addition, a model is developed in terms of one-electron orbital, to explain the characteristics of the PL excitation processes of V2+. Excitations with above and below band edge energy confirm the proposed schemes