Bias-Selective Dual-Operation-Mode Ultraviolet Schottky-Barrier Photodetectors Fabricated on High-Resistivity Homoepitaxial GaN

We demonstrate a dual-operation-mode ultraviolet (UV) Schottky-barrier photodetector (PD) fabricated on high-resistivity GaN homoepitaxial layer with low defect density. The undoped GaN active layer is grown by metal-organic chemical vapor deposition on a conductive bulk GaN substrate. Under reverse and zero bias, the PD works in depletion mode with low dark current and high UV/visible rejection ratio. Under forward bias, the PD works alternatively in photoconductive mode, which exhibits high photo-responsivity and an attractive narrow detection band around 365 nm. In addition, the PD also shows reasonable response speed in both operation modes.