X-Ray Detector Based on p⁺-Si/n-Zn₂SiO₄ Heterojunction Diode

p⁺-Si/n-Zn₂SiO₄ heterojunction diodes were fabricated on Si substrate, and tested as X-ray detector for the first time in this letter. The devices exhibited good rectification properties at dark current, and the dark current density was ∼ 5.6× 10^-6 A/cm² at -40 V. An obvious response to X-ray illumination (generated by bremsstrahlung with a tungsten target with tube voltage 30 kV) was observed at reversed bias, and the photo-to-dark ratio exceeding 480 was achieved. Furthermore, the detector exhibited both photoconductive behavior and photovoltaic behavior to switching X-ray illumination, and response time and recovery time are discussed on both mechanisms. In addition, the detector showed fast response time less than 200 ms and the linear outputs against incident X-ray dose rate from 0.383 Gy/s to 4.596 Gy/s at zero-bias voltage. The results imply that the ultra-wide band gap Zn₂SiO₄ based junction-type detectors have the potential for passive X-ray dose detection and nuclear battery cell applications.