Performance of Monocrystalline Diamond Radiation Detectors Fabricated Using TiW, Cr/Au and a Novel Ohmic DLC/Pt/Au Electrical Contact

We investigated the performance of synthetic high purity monocrystalline diamond radiation detectors fabricated with TiW, Cr/Au and a novel metallization technique utilising diamond-like carbon tunnelling junction and Pt/Au as electrical contacts. The investigation was carried out under irradiation with (60)Co gamma-rays, (90)Sr electrons and (241)Am alpha-particles. The experimental results with respect to I-V dark current levels, irradiation photocurrent, signal-to-noise ratio and time response have been compared and discussed. Results show an ohmic behaviour of the DLC/Pt/Au contact, a charge collection efficiency of 100% at an applied electric field of 0.377 V/mu m for all electrical contacts (under (90)Sr electrons irradiation) at a correspondent dark current value of less than a picoAmpere. The single crystal CVD DLC/Pt/Au diamond radiation detector reported here shows spectroscopic energy resolution of 1.1% at an applied voltage of +450 volts (0.9 V/mu m) under 5.5 MeV alpha particle irradiation. No 'memory' or 'pumping' effect was observed for the DLC/Pt/Au contact at positive bias; the signal was also stable (fluctuations below 0.5%) and reproducible under (60)Co irradiation, with a signal-to-noise ratio > 10000:1 and a linearity in the dose rate response.