Thermally Stimulated Investigations on Diamond Based Radiation Detectors

Abstract

Recent improvements in the chemical vapour deposition (CVD) technique have enabled the fabrication of detectors for particle as well as photon detection applications. However, according to the material quality, it has been shown that inherent defect concentration may induce significant deterioration of the detection signal. In order to gain better understanding of these effects, in this study we have investigated the presence of traps using thermally stimulated current (TSC) technique for CVD as well as for natural diamond. In the 100 to 550 K temperature range, TSC revealed six peaks or shoulders for CVD diamond material grown under different methane concentration. Four trapping levels at 0.3, 0.6, 0.87 and about 1.45 eV could be identified. For natural diamond, significant differences in the TSC spectra have been observed for two natural diamonds, used as radiation detectors. The correlation between the presence of trapping levels and the detection properties is discussed. Five energy levels, at 0.3, 0.45, 0.68, 0.78, and 1.37 eV could be identified in natural diamonds, whereas four of them were found to be associated with the poor radiation detection capabilities. Further, the effect of annealing treatments was studied for natural diamonds. The results of TSC investigations gave evidence of a trapping level that could be associated with an improvement of the detection properties.