High-Sensitivity Solar-Blind Photodetector Based on β-Ga2O3 Schottky Junction Under Forward and Reverse Bias

A Schottky junction solar-blind photodetector (PD) was fabricated on a $\beta $ -Ga2O3 film using ITO and Ni as interdigital electrodes. The ITO/ $\beta $ -Ga2O3/Ni PD showed a rectifying behavior which is attributed to the Ohmic contact of ITO/ $\beta $ -Ga2O3 and a Schottky contact of $\beta $ -Ga2O3/Ni. The ITO/ $\beta $ -Ga2O3/Ni PD has a high light-to-dark current ratio exceeding $10^{{4}}$ under both forward and reverse bias due to the intrinsic energy-band structure of $\beta $ -Ga2O3, in which no shallow defect energy levels exist. Under a forward bias of 20 V and 254 nm illumination ( $40.94 \mu \text{W}$ /cm $^{{2}}{)}$ , the ITO/ $\beta $ -Ga2O3/Ni PD has a high responsivity, detectivity, and external quantum efficiency of 470.62 A/W, $1.11\times 10^{{15}}$ Jones, and $1.67\times 10^{{5}}$ %, respectively. The relative decrease in performance in reverse bias compared with forward bias is attributed to the increased Schottky barrier of Ni/ $\beta $ -Ga2O3. In addition, the photocurrent changes almost linearly with applied bias and optical power, indicating that the $\beta $ -Ga2O3 film has fewer traps and carrier-recombination centers. Therefore, planar ITO/ $\beta $ -Ga2O3/Ni PDs are good candidates for monitoring solar-blind radiation.