GaN schottky barrier photodetectors with a β-Ga₂O ₃ cap layer

GaN Schottky barrier UV photodetectors (PDs) with a β-Ga ₂O₃ cap layer realized by furnace oxidation of GaN epitaxial layer were fabricated and characterized. With the cap layer inserted, it was found that the reverse leakage current could be reduced by more than 4 orders of magnitude and the UV-to-visible rejection ratio increased by 21 times. When compared with the conventional GaN PDs, incorporating an additional β-Ga₂O₃ cap layer helps to reduce the noise level and at the same time achieve a larger detectivity.