Growth and characterization of Ga ₂O ₃ on sapphire substrates for UV sensor applications

The β-Ga ₂O ₃ films were grown on (0001) sapphire at 500°C by metal organic chemical vapor deposition. In the analysis of crystal structure, we found that the (-201) oriented single crystal β-Ga ₂O ₃ epilayer can be obtained under low chamber pressure of 15 torr. Moreover, a metal-semiconductor-metal solar-blind deep ultraviolet photodetector was fabricated with the β-Ga ₂O ₃ epilayer. As the bias voltage is 5 V, the photodetector exhibits a relatively low dark current about 0.2 pA, which induced by the highly resistive nature of the β-Ga ₂O ₃ thin films. From the responsivity result, it can be observed that photodetector shows a maximum responsivity at 260 nm, revealing the β-Ga ₂O ₃ photodetector was really solar-blind. The responsivity of the photodetector was as high as 20.1 A/W with an applied bias of 5 V and an incident light wavelength of 260 nm. The improved performance is attributed to the high quality of β-Ga ₂O ₃ epilayer.