Photoluminescence evaluation of the quality of Cd_0.9Zn_0.1Te detectors doped with different indium concentrations

Abstract

With the aim to determine an optimal indium (In) concentration in Cd 0.9 Zn 0.1 Te:In nuclear radiation detectors for a good material quality, low-temperature photoluminescence (LTPL) measurements have been performed at 5 K in the energy range of 1.2-1.7 eV. The LTPL spectrum of initial sample contained a neutral acceptor bound exciton (A 0 X) peak at 1.635 eV, donoracceptor pair (DAP) peak at 1.606 eV with its 1LO phonon replica, and deep-level defects (D) peak at 1.455 eV. In doping leads to the appearance of a new relatively intensive peak at 1.652 eV that is caused by a shallow neutral donor bound exciton (D 0 X) due to In substituting cadmium vacancies (V Cd ). At In concentrations of about 8 Â 10 16 -10 17 cm À3 the value of I D 0 X =I D ratio is maximal, which indicates a low density of detrimental carrier traps and, therefore, high-material quality.We believe that at such concentrations the majority of as-grown Cd vacancies will be substituted by In atoms and, therefore, noted concentrations are optimal, which was confirmed by the correlation with mobility-lifetime product.