Wavelength- and intensity-tunable self-powered bipolar photodetectors based on a-Ga2O3 heterostructures for encrypted communication

Bipolar photodetectors are promising for optical logic and communication but often suffer from structural complexity and high power consumption. Here, we report a self-powered, vertical photodetector based on an ITO/Au NPs/a-Ga2O3/Pt heterojunction. By leveraging Au nanoparticles to engineer interfacial oxygen vacancies and the synergistic modulation of the Schottky barrier by the light field, the device achieves a distinct bidirectional photoresponse at zero bias. Specifically, it exhibits wavelength-dependent polarity switching, generating positive photocurrent at 254 nm and negative at 310 nm. Notably, under 295 nm illumination, the device displays an anomalous intensity-dependent polarity reversal, transitioning from negative to positive as light intensity increases. We demonstrate the potential of these tunable features in optical logic gates and encrypted communication systems, offering a new pathway for multifunctional self-powered optoelectronics.