Direct hard X-ray photodetector with superior sensitivity based on ZnGa2O4 epilayer grown by metalorganic chemical vapor deposition
Siddharth Rana, Shang‐Jui Chiu, Chih‐Yang Huang, Fu-Gow Tairtan, Yan‐Gu Lin, Dong‐Sing Wuu, J. P. Singh, Guang-Cheng Su, Po−Liang Liu, Ray‐Hua Horng
Abstract
In this work, we have fabricated a highly sensitive direct irradiating X-ray photodetector (DXPD) based on Zinc Gallium Oxide (ZnGa 2 O 4 ) epilayers with a metal-semiconductor-metal structure. The ZnGa 2 O 4 epilayers were grown on a c-plane sapphire substrate by metalorganic chemical vapor deposition (MOCVD). To test the DXPD's capabilities, we subjected it to a synchrotron hard X-ray source with an energy of 10 keV, and measured incident radiation flux ranging from 5.7✕10 7 to 4.6 ✕10 11 counts/sec. The effect of changing the applied bias voltage on the time response of the DXPD was investigated. The sensitivity of hard XPDs was compared using gallium oxide (β-Ga 2 O 3 ) epilayer grown by MOCVD. The results showed that ZnGa 2 O 4 DXPD had approximately 10 4 times greater sensitivity than the β-Ga 2 O 3 based XPD. ZnGa 2 O 4 based detectors also exhibited remarkable sensitivity of 2.87 × 10 9 μC Gy air −1 cm −2 for the incident flux of 5.7✕10 7 counts/sec at 15 V. Additionally, the sensitivity was examined in terms of applied bias and dose rate. Based on these observations, it can be concluded that ZnGa 2 O 4 epilayers grown by MOCVD hold immense potential for use in high-performance hard XPDs.