CVD diamond devices for charged particle detection

A (1 0 0)-oriented chemical vapour deposited (CVD) diamond film was grown by using a hot-filament chemical vapour deposition technique and then fabricated as an alpha particle detector. The current characteristics indicate a fine Ohmic contact for bias voltage up to 150 V. The dark current and the net current induced by α particles of ~16.0 nA and ~6.9 nA, respectively, are achieved at 100 V. The net current initially increases linearly with voltage and irradiation time, and then levels off, due to the 'polarization' effect. After irradiation, the dark current increases due to the release of captured carriers in shallow energy levels. The response of the CVD diamond detector to 5.5 MeV α particles demonstrates clearly that the 'polarization' and 'priming' effects intensively affect the detector performance. By pre-irradiating the detector with β particles, the charge collection efficiency is dramatically improved from 19.38% to 36.91% due to the 'priming' effect of the deep traps.