Dual-band deep ultraviolet AlGaN photodetectors

The design, fabrication and characterisation of a back-illuminated voltage bias selectable dual-band AlGaN UV photodetector are reported. The photodetector can separate UV-A and UV-B band radiation by bias switching a two-terminal n–p–n homojunction structure that is fabricated in the same pixel. When a forward bias is applied between the top and bottom electrodes, the detector can sense UV-A (315–400 nm) and reject UV-B (280–315 nm) band radiation. Alternatively, under reverse bias, the photodetector can sense UV-B and reject UV-A band radiation.