High-performance diamond soft-X-ray detectors with internal amplification function

We have characterized the performance of soft-X-ray detectors fabricated with high-quality chemical-vapor-deposition (CVD) diamond layers which were homoepitaxially grown on high-pressure/high-temperature-synthesized Ib-type (100) substrates by means of a high-power microwave plasma CVD method. The soft-X-ray detectors with thin (≈ 15 nm) titanium-nitride interdigitated electrodes were fabricated using a standard photolithography process. We have found that the signal currents significantly increased at sufficiently higher voltages which were applied to the electrodes. The apparent room-temperature quantum efficiencies estimated at the applied voltage of 100 V from the signal currents attained by the diamond-based detector for a photon irradiation rate of ≈ 4 × 106 photons/s ranged from 3.2 × 105 to 3.1 × 106 with photon energies ranging from 400 to 1800 eV. In addition, the diamond detector had signal-to-noise ratios larger than 6 orders of magnitudes. Thus, the present diamond detector has been verified to have excellently high sensitivities to soft-X-ray photons. The internally amplifying function of the diamond detector is discussed.