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.