In this paper, two types of detectors, one with a coplanar and the other with a sandwich geometry using an identical CVD diamond film, are fabricated in order to investigate the effects of the film microstructure on the performance of diamond film α-particle detectors. An average charge collection efficiency of 42.9% for the coplanar structure and of 37.4% for the sandwich structure detectors is obtained, respectively. Raman scattering studies directly demonstrate that the different counts, collection efficiencies and photocurrents of the two types of detectors mainly result from the different micro-structural features between the final growth side and the nucleation side of the diamond film. Under α particle irradiation the detector with sandwich geometry has a similar trend on energy resolution with coplanar geometry under different applied electric field. A good energy resolution of 1.1% is obtained for both detectors.
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