Compensation origins in II–VI CZT materials

It is well known that II–VI CdTe, and CdZnTe (CZT) materials suffer from the presence of cadmium vacancies (V-Cd) and their complexes with impurities and defects, which lead to low resistivity and trapping. These defects are known generally as the A-centers, around 0.1–0.2 eV. In order to increase the resistivity, intentional and non intentional chemical and physical compensations are conducted; for CdTe, halogens (Cl, Br, I) or In are generally used, while for CZT, the compensation origins are still unknown. In this paper, we try to study the compensation by measuring deep levels and very shallow levels at temperatures as low as helium temperature by photoluminescence (PL) and photoinduced current transient spectroscopy (PICTS), and model the resistivity in order to clarify the origins of the compensation and the high resistivity in CZT materials.