Design of Band-Engineered Bidirectional Avalanche Photodetector Enabling Switchable Dual-Band Ultraviolet Detection

The integration of multi-dimensional detection and signal amplification provides new opportunities for highly sensitive photoelectric detection. In this work, we present, to the best of our knowledge, the first GaN-based bidirectional avalanche photodetector capable of dual-band ultraviolet detection. The device features two avalanche photodiodes facing each other and sharing a mutual p-layer, enabling avalanche multiplication under both forward and reverse bias voltages. In forward mode, the device exhibits a detection cutoff at 365 nm, while in reverse bias mode, it reaches a cutoff at 281 nm in the solar-blind ultraviolet range. The carrier multiplication and transport mechanisms in the bidirectional operating mode are also clearly demonstrated. This dual-band detection approach is significantly conductive to accurate signal recognition. More importantly, the design concept is not restricted to the nitride UV material system but can be extended to a wide range of photoelectric materials capable of forming p-n junctions, paving the way for the development of advanced photoelectric devices.