Flexible Solar-Blind Ga2O3 Ultraviolet Photodetectors With High Responsivity and Photo-to-Dark Current Ratio

In this work, flexible solar blind Ga
₂
O
₃
ultraviolet photodetectors with high responsivity and photo-to-dark current ratio are demonstrated. The Ga
₂
O
₃
films are obtained by the RF magnetron sputtering method on flexible polyimide (PI) substrates and the results demonstrate that all the films grown under various temperatures are amorphous. When the incident light wavelength is less than 254 nm, the incident light is effectively absorbed by the Ga
₂
O
₃
film. By controlling the growth temperature of the material, the responsivity and photo-to-dark current ratio of the corresponding metal-semiconductor-metal photodetectors are significantly improved. At growth temperature of 200 °C, the current under 254 nm illumination obtains 396 nA at voltage of 20 V (corresponding responsivity is 52.6 A/W), the photo-to-dark current ratio is more than 10
⁵
, and the external quantum efficiency reaches 2.6 × 10
⁴
%, which is among the best reported Ga2O3 ultraviolet photodetectors including the devices on the rigid substrates. After the bending and fatigue tests, the flexible detectors have negligible performance degradation, showing excellent mechanical and electrical stability.