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Abstract: 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. [Copyright &y& Elsevier]

Abstract: In order to grow diamond film on alumina ceramic, it is essential to control the diamond nucleation properly. Under a gas pressure lower than that used for growth, a high nucleation density of diamond films on alumina, as high as 108/cm2, is successfully achieved by microwave plasma-enhanced chemical vapor deposition method. Based on this, [100]-textured diamond films are successfully deposited on alumina by controlling the substrate temperature. From the results on SEM, XRD and Raman measurements, the substrate temperature has a strong influence on the textured growth and quality of diamond films on alumina substrates. Too low or too high temperature cannot obtain [100]-textured and good-quality films. The optimum substrate temperature range, for the growth of [100]-textured and good-quality diamond films on alumina, should be 800∼860 °C in our experiments. [Copyright &y& Elsevier]

Abstract: Due to different oriented diamond films having different properties, in this paper optical and electrical properties of different oriented diamond films have been investigated. The measured results indicate diamond films are of high quality and the properties of the (001)-oriented diamond film are better than those of the (111)-oriented one. Refractive index and extinction coefficient of (001)-oriented diamond film in the wavelength range of 2.5–12.5μm is 2.391 and in the order of 10−5, respectively. And for the (111)-oriented one it is 2.375 and in the order of 10−4. The dark current of the (001)-oriented diamond film is 33.7nA under an applied electric field of 100kV/cm. The resistivity of the (001)-oriented diamond film obtained is about 2.33×1010 Ωcm. The current of (001)-oriented diamond film is almost no change with the time testing. [Copyright &y& Elsevier]

Abstract: The surface roughness and optical properties of diamond films untreated and treated by activated hydrogen have been investigated. After hydrogen ion treatment the surface of the film is modified effectively. Optical properties of the treated film are better than those of the untreated one. [Copyright &y& Elsevier]

Abstract: We reported the growth and its electrical properties of [100]-oriented diamond film using alcohol and hydrogen by HFCVD. SEM and Raman measurements indicated that high quality polycrystalline diamond films with [100]-faced structure were obtained. Dark current–voltage (I–V), capacitance–frequency (C–F), capacitance–voltage (C–V) and photocurrent under steady-state 55Fe 5.9keV X-ray excitation of freestanding diamond film were investigated at room temperature. Results indicated that after post-annealing for [100]-oriented diamond films dark current was in the order of 10−10 A and the photocurrent was of in the order 10−8 A by X-ray irradiation with the applied voltage of 40V, capacitance and dielectric loss were very small with the value of 2pF and 2×10−3 with the bias voltage of 0.05V, respectively, and almost had no variation with the change of frequency in high frequencies from 100kHz to 10MHz. [Copyright &y& Elsevier]

Abstract: The polycrystalline nature of the films has limited the improvement of CVD diamond radiation detectors. In this work, three CVD diamond films with different microstructures were grown by a hot-filament chemical vapor deposition (HFCVD) technique and were fabricated as CVD diamond radiation detectors. The photocurrents and the pulse height distributions (PHDs) obtained by the detectors were measured by using 5.9keV 55Fe X-rays. The dark-current of 16.0nA and the photocurrent of 15.9nA are achieved at a bias voltage of 100V. The PHD peak is well separated from the noise and a better energy resolution of 21.2% is obtained due to the high ratio of grain size to the film thickness. The time-dependent photocurrent initially increases rapidly and then levels off due to the ‘polarization’ effect. [Copyright &y& Elsevier]

Abstract: By using different deposition conditions, four CVD diamond films with different qualities and orientation were grown by the hot-filament CVD technique. The dielectric properties of these films before and after annealing were investigated in detail. A study of the relationship between the different deposition conditions and annealing process with respect to the dielectric properties was carried out. These CVD diamond films were also characterized with Raman spectroscopy, XRD and characteristics. High-quality CVD diamond films were grown on Si substrate mechanically scratched with diamond powder. The annealing process reduces the hydrogen contamination of the films and therefore improves the film quality. CVD diamond films with good electric properties such as a resistivity of 1.2×1011Ωcm at a voltage of 50V, a dielectric constant of 5.73 and a dielectric loss of 0.02 at a frequency of 2MHz were obtained. [Copyright &y& Elsevier]