High performance solar-blind ultraviolet photodetector based on ITO/β-Ga₂O₃ heterostructure

Abstract

Abstract The authors report an indium tin oxide (ITO) decorated solar-blind deep ultraviolet photodetectors (PDs) based on high quality β -Ga 2 O 3 single crystal microwires (MWs). An ultrahigh photo-to-dark current ( I photo / I dark ) ratio ∼10 7 of the PDs has been realized. Compared with In/ β -Ga 2 O 3 /In metal-semiconductor-mental (MSM) PD, the device with ITO as the interlayers between In and β -Ga 2 O 3 show excellent performances, such as the high responsivity of 1720.2 A W −1 and 438.8 A W −1 under 260 nm illumination with reverse and forward bias, respectively. In addition, the device exhibited a very low dark current as low as 2.0 × 10 −13 A and a photocurrent up to 1.0 × 10 −6 A at the bias of −6 V (under 1.95 mW cm −1 @260 nm). The rise and fall time of the device were 0.5 s and 0.2 s, which was significantly faster than MSM structure. Moreover, the device exhibited an ultrahigh solar-blind/visible rejection ratio ( R 260 nm / R 400 nm ) of 1.09 × 10 5 , a detectivity D * of 1.23 × 10 14 Jones and the external quantum efficiency of 4180.3%. The excellent performances of the PDs are attributed to the improved carrier separating process at the ITO/ β -Ga 2 O 3 interfaces and the reduced carrier trapping behavior induced by the β -Ga 2 O 3 surface states. The introduction of ITO between MWs and the electrodes is of great significance for the application of β -Ga 2 O 3 based detectors.