Thermally stimulated current investigations on diamond x-ray detectors

Natural II-a type diamond is increasingly used for the fabrication of radiation detectors. However, the presence of inherent defects has a strong impact on the detector characteristics such as the time-dependent stability of the detection signal. In order to draw better insight into this effect, comparative investigations of the x-ray responses with thermally stimulated current (TSC) measurements were carried out on natural diamond detectors. TSC revealed the presence of four peaks or shoulders on natural samples in the 200-500 K domain. Three energy levels were identified at about 0.7, 0.71, and 0.95 eV. Time-dependent x-ray detector sensitivity was investigated for various initial conditions. The results give evidence of the improvement of the detection properties after having filled traps in the material by x-ray irradiation. The comparison between the x-ray response and the TSC spectra indicates that trapping levels emptied at room temperature appear to significantly affect the performance of radiation detectors.