Zero-bias operation and beam energy dependence of diamond sensors

A prototype sensor able to work at zero bias has been fabricated using high quality single crystal diamond and two Schottky junctions. The detector's current in the dark is 3.2 +/- 0.2x10(14) A, while the current measured under irradiation with 1.6 Gy center dot min(-1) of 6 and 15 MV x-ray photons is 7.5 +/- 0.2x10(-10) A. The sensitivity is strongly dependent on the applied voltage whereas at zero bias we have measured 37 +/- 2 nC center dot Gy(-1), independent of the beam quality. The sensitivity increases with a sub-linear trend up to 100V, as the sensor photocurrent dependence on voltage. Moreover, the device shows very fast response on the rise and fall transients, with the signal stability under irradiation better than 0.3%. The linearity with the dose rate is spread over three orders of magnitude from 1.3 x10(-3) Gy center dot min(-1) to 1.2 Gy center dot min(-1) as measured with Co-60 photons.