Point defects: Their influence on electron trapping, resistivity, and electron mobility-lifetime product in CdTexSe1−x detectors

Abstract

In this research, we assessed the abundance of point defects and their influence on the resistivity, the electron mobility-lifetime (μτe) product, and the electron trapping time in CdTeSe crystals grown under different conditions using the traveling heater method. We used current-deep level transient spectroscopy to determine the traps' energy, their capture cross-section, and their concentration. Further, we used these data to determine the trapping and de-trapping times for the charge carriers. The data show that detectors with a lower concentration of In-dopant have a higher density of A-centers and Cd double vacancies (VCd- -). The high concentrations of VCd- - and A-centers, along with the deep trap at 0.86 eV and low density of 1.1 eV energy traps, are the major cause of the detectors' low resistivity, and most probably, a major contributor to the low μτe product. Our results indicate that the energy levels of point defects in the bandgap, their concentrations, capture cross-sections, and their trapping and de-trapping times play an important role in the detector's performance, especially for devices that rely solely on electron transport.