Optical And Electronic Performances Of CVD Diamond Film And Its Applications In Radiation Detectors

The outstanding properties of CVD diamond film such as electronic, optical, thermal and mechanical and the high radiation hardness have made it an ideal candidate material for radiation detectors in severe environments. Fabrication of 'detector grade' CVD diamond films and development of CVD diamond detectors have been leading edge subjects. Micro-Strip Gas Chamber (MSGC) fabricated on CVD diamond substrate would overcome the charge-up effect and the substrate instability, which has been a hotspot in the research of gas detectors.In this thesis, 'detector grade' (100)-oriented CVD diamond films were successfully grown on Si substrates by manually scratching the Si surface with the diamond powder and controlling the hot-filament chemical vapor deposition (HFCVD) parameters. The ratio of the diamond grain size to the film thickness is high to 50%, much larger than the reported values of 10-20% in literatures. The optical and electronic performances of CVD diamond film and the defect energy-levels in the film were investigated in detail. We firstly detected the defect energy-level at 1.55 eV by using the PL spectrum and tentatively attributed it to the zero-phonon luminescence line (ZPL) or vibronic band of the [Si-V]° induced by the Si-O bonds. The film quality was improved by the annealing process and the surface oxidization. Cr/Au electrodes were realized ohmic contacts with diamond after annealing.A general read-out electronic system, i.e. a computer assistant multi-channel spectroscopy was designed and set up for CVD diamond detector and MSGC. ANSYS software was used to simulate the distribution of the electric field in CVD diamond micro-strip detector and MSGC and to optimize the electrode design.We successfully developed CVD diamond X-ray detectors and a particle detectors. 5.9keV 55Fe X-rays and 5.5MeV 241Am a particles were used to measure the performances of CVD diamond detectors. The internal relationship between the detector performances and the material quality (especially the diamond grain size) was obtained and the "priming" effect was studied to improve the detector performances. At an electric field of 50kV cm-1, many significant results were achieved, e.g. the dark-current is of 3.2nA, the photocurrent of 16.8nA (X-rays) and the net-current of 15.0nA (a particles), the signal-to-noise ratio of 5.25 (X-rays) and 4.69 (a particles), the energy resolution of 16.26% (X-rays) and 25% (a particles), the charge collection efficiency of 45.1% (X-rays) and 19.38% (a particles) and so on. By pre-irradiating CVD diamond a particle detector with β particles, the charge collection efficiency was dramatically improved from 19.38% to 36.91% due to the 'priming' effect of the deep trapping centers. CVD diamond micro-strip a particle detector was also advanced on a free-standing CVD diamond film and the charge collection efficiency of 46.1% and...