Thermally stimulated current observation of trapping centers and their distribution in as-grown TlGaSeS layered single crystals

Abstract

Thermally stimulated current (TSC) measurements were carried out in as-grown TlGaSeS layered single crystals. The investigations were performed in temperatures ranging from 10 to 160 K with heating rate of 0.8 K s −1. The analysis of the data revealed three electron trap levels at 13, 20 and 50 meV. The activation energies of the traps have been determined using various methods of analysis, and they agree with each other. The calculation for these traps yielded 3.3 × 10 −24, 1.0 × 10 −24, and 1.1 × 10 −24 cm 2 for capture cross-sections and 1.9 × 10 12, 2.9 × 10 11 and 4.5 × 10 10 cm −3 for the concentrations, respectively. It was concluded that in these centers retrapping was negligible, as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping. An exponential distribution of electron traps was also revealed from the analysis of the TSC data obtained at different light excitation temperatures. This experimental technique provided values of 9 and 77 meV/decade for traps distribution of peaks A and C, respectively.