Influence of temperature on the response of diamond radiation detectors

The response of chemically vapor deposited diamond detectors under alpha particle irradiation was studied as a function of operating temperature in the 20-280°C range. The detector characteristics were studied for two initial states: (i) the detector being either preirradiated under x-rays at a dose of 8 Gy (pumped state) or (ii) preannealed at 400°C for 15 min (depumped state). Pumped detectors were found to exhibit a stable response (evaluated by measurement of the charge collection efficiency η) with temperature up to 120°C, above which a decrease of η was observed. Preannealing at 400°C was shown to induce, at room temperature, a drastic deterioration of the detector response, when compared to that of pumped devices, whereas above 150°C a reversed trend was observed. Correlations between the response of the diamond detectors and the presence of traps were determined by comparing the detector response for α particles with the thermally stimulated current (TSC) spectrum. The temperature dependence of the detector response was shown to be related to the presence of a trapping level measured around 260°C by TSC.