A High-Resistivity ZnO Film-Based Photoconductive X-Ray Detector

Abstract

High-resistivity ZnO film-based photoconductive detectors have been fabricated on glass substrate by the magnetron sputtering growth method, and tested as X-ray detectors for the first time in this letter. The devices exhibited a low dark current ~ 100 pA at 40 V bias and a fast transient reproducible response to X-ray illumination (generated by bremsstrahlung with a tungsten target with tube voltage 30 kV) ~ 200 ms, which was mainly attributed to the high resistivity ~ 109Ω cm of the ZnO film deposited in the oxygen atmosphere. The high resistivity was due to the zinc vacancy defects' compensation with the n-type defects in ZnO film as revealed by photoluminescence spectra. Furthermore, the detector achieved an X-ray pulse detection, and the rise time and full width at half maximum of the outputs signal were 139 μs and 0.9 ms at 200 V bias, respectively. Associated with material characterizations, it was demonstrated that the high-resistivity ZnO film detector had the potential to be promising for fast X-ray detection application.