The excellent performance of β-Ga2O3 Schottky photodiode under forward bias and its application in solar-blind ultraviolet communication

In this work, the planar β-Ga2O3 Schottky photodiodes on the sapphire substrates were manufactured by conventional photolithography and lift-off processes. Au and Ti/Au were used as Schottky and Ohmic contacts. After optimizing the geometry layout of β-Ga2O3 Schottky photodiode, R increased by 120%, EQE enhanced by 896.81% and D* gotten a 1540.88% increase. Particularly, β-Ga2O3 Schottky photodiode had exhibited the abnormally excellent performance under forward bias, contrary to most of conventional UV photodetectors. The origin of abnormally excellent performance in β-Ga2O3 Schottky photodiodes under forward bias have been researched systematically. Combined experiments with DFT calculations, we have attributed the ultra high EQE in β-Ga2O3 Schottky photodiode to its unique band structure. While the large photo-to-dark current ratio and D* under forward bias originate from deep-state intrinsic defects of β-Ga2O3. At last, the solar-blind ultraviolet communication system based on β-Ga2O3 Schottky photodiode was achieved and the message, “Hello, HIT!”, was successfully transmitted.