Radiation detector made of a diamond single crystal grown by a chemical vapor deposition method

The first investigation of a radiation detector made of a diamond single crystal grown by a chemical vapor deposition (CVD) method was successfully carried out. The diamond single crystal, having a size of 2.0 x 2.0 x 0.7 mm(3), was grown by the CVD method and then applied to the detector. The CVD method was able to reduce nitrogen and boron impurities in diamond crystals more effectively than a high-pressure and high-temperature (HP/HT) method. Consequently the detector had high-energy resolution of 0.4% for 5.486 MeV alpha particles from an Am-241 source. The behavior of charge carriers in the detector could not be adequately investigated because the detector had a partial depression layer and strong rectification. Ionization energy of the CVD diamond was determined to be 16.1 eV; this value was higher than that of the HP/HT type IIa diamond, i.e., 13.1 eV. This result shows the potential of CVD diamond single crystals because an ideal diamond should have higher ionization energy than the HP/HT type IIa diamond that had the influence of impurities. (C) 2003 Elsevier Science B.V. All rights reserved.