High-Sensitivity Solar-Blind Photodetector Based on -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 104 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 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 x 10(15) Jones, and 1.67 x10(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.