Trapping and detrapping effects in high-quality chemical-vapor-deposition diamond films: Pulse shape analysis of diamond particle detectors - art. no. 195205

An analysis of the time evolution of the response of diamond particle detec tors is carried out, using as a probe 5.5 MeV alpha particles impinging on high-quality diamond films grown by microwave chemical vapor deposition (CV D). Both the amplitude and the time evolution of the pulses are shown to ch ange drastically when the detector is preirradiated with beta particles (pu mping), a slow component developing after pumping, indicating carriers trap ping and releasing (detrapping). Pulse shapes obtained for positive and neg ative detector polarities are compared in both the as-grown and pumped stat es. The presence of at least two trapping centers for holes is necessary to explain the results, the shallower having an activation energy of about 0. 3 eV. The effects of pumping are clarified, and the different role played b y electrons and holes is evidenced. We modify a previous model for trapping -detrapping behavior originally applied to Si(Li) detectors to describe the more complex behavior of CVD diamond detectors, and develop a computer sim ulation based on it. The simulated pulse shapes agree very well with experi ment with reasonable values of the physical parameters involved, making thi s technique helpful for studying and identifying defects which are responsi ble for limitation of the efficiency of CVD diamond particle detectors. Fie ld-assisted detrapping seems to take place for fields of about 10(4) V/cm.