Low-temperature thermoluminescence study of GaSe: Mn layered single crystals

Mangan doped GaSe single crystals have been studied by thermoluminescence measurements performed with various heating rates between 0.4 and 1.0 K/s in the temperature range of 10-300 K. Thermoluminescence spectra exhibited four distinguishable peaks having maximum temperatures at 47, 102, 139 and 191 K revealing the existence of trapping levels in the crystals. Curve fitting and initial rise methods were applied to observed peaks to determine the activation energies of four trapping levels. Capture cross-sections of each level were also evaluated using the obtained energy values. Moreover, heating rate dependencies of the obtained peaks were investigated. It was shown that increase in the heating rate resulted in the decrease in thermoluminescence intensity and shift of the peak maximum temperatures to higher values. Discrete, single trap behaviour was established for acceptor level related with the peak at 191 K by analysing the sequentially obtained peaks with different stopping temperatures between 15 and 65 K.