Diamond film-based particle detectors

Diamond films grown by microwave plasma enhanced chemical vapor deposition have been investigated as particle detectors for nuclear physics. A CH(4)-CO(2) gas mixture was used as gas feed during the growth process. The film morphology, preferential orientation and crystal quality were systematically changed by varying the deposition parameters. In particular, the substrate temperature, T(s), and the CH(4) concentration in the gas mixture were chosen in the 750-850 degrees C and 47-50% ranges, respectively. The resulting films were characterized by X-ray diffraction and scanning electron microscopy. The correlation of the above structural properties with the response of the diamond-based detectors was then extensively studied. To this purpose, they were irradiated with a 5.5 MeV (241)Am alpha particle source under different applied electric fields and their collection lengths and efficiencies were compared. In particular, it was found that the limiting factor in the detector performances is related to intra-grain trapping centers, whose effectiveness is increasingly higher when the sample preferential orientation tends to (100) texturing or moving away from the Si-diamond interface. (C) 1998 Elsevier Science S.A.