X-ray detectors based on p+-Si/n-ZnO abrupt heterojunctions

ZnO is a direct wide-band gap semiconductor with Eg=3.3 eV, which has high saturation velocity and is radiation tolerant as well. It can be expected being utilized for the room temperature nuclear radiation detector. In this paper, we fabricate the p+-Si/n-ZnO abrupt heterojunction and study the X-ray detection properties. The I-V characteristics were measured in the temperature range of -40 °C-40 °C. The built-in potential and the interface state density are separately calculated to be 0.25 eV and 2.1×1011 cm^-2 from the temperature dependent dark current. The detector exhibits photovoltaic behavior and shows linear photo-current response to the incident X-ray intensity. The open-circuit voltage is 0.21 V and the short-circuit current is 0.15 μA under the X-ray dose rate of 1.53 Gy/s. The sensitivities of the detector are 95 nC/Gy and 115 nC/Gy at the bias voltages of 0V and -5V respectively. The transient response presents the fast and stable response of the detector to the X-ray.