Effects of the polarity of bias voltage on the electrical performance of the diamond film detectors

The effect of the polarity of the applied bias voltage on the electrical response and the charge collection efficiency of sandwich structural diamond film detectors under 5.5 MeV 241Am alpha-particle irradiation is investigated. Results show that, under the alpha irradiation the detector applied with a negative bias voltage has a higher response current and a better signal-to-noise ratio than that applied with a positive bias voltage. A better energy resolution of about 25.0% is obtained for the detector applied with a negative bias voltage, and however 38.4% for that with a positive bias voltage. Raman scattering studies demonstrate that these changes with the polarity of the bias voltage may be attributed to the different structural imperfection distributions along the thickness direction of the diamond film.