A large-grain-size thick-film polycrystalline diamond detector for x-ray detection

A diamond film with a size of 6 x 6 x 0.5 mm(3)is fabricated by electron-assisted chemical vapor deposition. Raman spectrum analysis, x-ray diffraction and scanning electron microscope images confirm the high purity and large grain size, which is larger than 300 mu m. Its resistivity is higher than1012 omega cm.<iInterlaced-finger electrodes are imprinted onto the diamond film to develop an x-ray detector. Ohmic contact is confirmed by checking the linearity of its current-voltage curve. The dark current is lower than 0.1 nA under an electric field of 30 kV cm(-1). The time response is 220 ps. The sensitivity is about 125 mA W(-1)under a biasing voltage of 100 V. A good linear radiation dose rate is also confirmed. This diamond detector is used to measure x-ray on a Z-pinch, which has a double-layer 'nested tungsten wire array'. The pronounced peaks in the measured waveform clearly characterize the x-ray bursts, which proves the performance of this diamond detector.