Theoretical Analysis and Verification of Electron-Bombardment-Induced Photoconductivity in Vacuum Flat-Panel Detectors

Vacuum flat-panel detectors (VFPDs) using a cold cathode and photoconductor have important applications in large-area photodetectors; however, the mechanism for achieving high photoresponsivity must be further explored. In this article, theoretical analysis was performed to examine the electron-bombardment-induced photoconductivity (EBIPC) effect based on the equivalent circuit model. Formulas for photo/dark current were derived, which indicated that carrier multiplication was mainly due to energetic electron bombardment. The theoretical formulas also revealed the carrier multiplication mode inside the photoconductor of VFPDs and the relationship between the responsivity and device parameters. To verify the theoretical results, VFPDs with a ZnS photoconductor and ZnO nanowire cold cathode were studied. The responsivity initially increased and then decreased by increasing the photoconductor thickness. In addition, a broad dynamic range was achieved with a linear dynamic range of 106.02 dB, which was attributed to the efficient collection of carriers induced by EBIPC at the optimized thickness. Our theoretical results were validated by the experimental results and can provide guidance for developing VFPDs based on EBPIC.

Automated summary

"This study examines the mechanism of electron-bombardment-induced photoconductivity in vacuum flat-panel detectors and derives relevant formulas, validating the theoretical results and providing guidance for the development of VFPDs based on EBPIC."