Characterisation of a coplanar CVD diamond radiation detector

Studies have been made of the performance of polycrystalline CVD diamond for use as a radiation detector in high temperature or high radiation environments. In this work, we have fabricated a coplanar CVD diamond detector consisting of inter-digitated metal electrodes deposited only on the ‘growth’ side of the diamond film. This device geometry produces lateral electric field distributions close to the growth surface of the film, where the diamond crystallites are significantly better ordered and largest in size. Pulse height spectra were acquired using a 241Am alpha particle source which showed a broad full-energy peak corresponding to a charge collection efficiency of approximately 15%. The X-ray response of the detector was also measured using a silver anode X-ray generator. The observed photocurrent showed a slow time evolution before reaching a steady value, indicating the presence of significant charge traps in the material. The measured sensitivity of the detector to 30 kV(peak) X-rays was 2.1×10−5 C/Gy.