【Device Papers】Reverse-bias driven anomalous polarity switching in FeSi₂/Ga₂O₃-NRs heterojunction based solar-blind photodetector

      Researchers from the Indian Institute of Technology Ropar have published a dissertation titled "Reverse-bias driven anomalous polarity switching in FeSi₂/Ga₂O₃-NRs heterojunction based solar-blind photodetector" in Applied Surface Science.

Abstract

      Recently, polarity-switching photodetectors have attracted significant attention due to their ability to reverse photocurrent direction based on the incident light wavelength or applied bias. This unique functionality makes them promising for applications in optical logic operations, optically controlled artificial synapses, and dual-channel communication. Most of the reported polarity-switching devices have a wavelength dependent switching, while voltage-driven switching is rare to find, especially for narrowband devices such as those used for secure UV-C communications. In this work, we present a FeSi₂/Ga₂O₃-NRs heterostructure photodetector that demonstrates polarity-switching behavior only under an applied reverse bias. Under 254 nm illumination, the device exhibits a photocurrent direction change from negative to positive, offering a novel approach for encrypted solar-blind detection. The band alignment analyzed via X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM) is used to understand the underlying working mechanism. Additionally, the device exhibits high stability in performance even after 1 year of ambient storage without encapsulation. The demonstrated polarity-switching behavior in this solar-blind photodetector provides a pathway for encrypted optical signal processing and secure UV-C imaging with minimal background noise in the ambient condition.

DOI：

https://doi.org/10.1016/j.apsusc.2025.165340