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

Abstract

The authors report an indium tin oxide (ITO) decorated solar-blind deep ultraviolet photodetectors (PDs) based on high quality β-Ga2O3 single crystal microwires (MWs). An ultrahigh photo-to-dark current (I photo/I dark) ratio ∼107 of the PDs has been realized. Compared with In/β-Ga2O3/In metal-semiconductor-mental (MSM) PD, the device with ITO as the interlayers between In and β-Ga2O3 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 × 105, a detectivity D* of 1.23 × 1014 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-Ga2O3 interfaces and the reduced carrier trapping behavior induced by the β-Ga2O3 surface states. The introduction of ITO between MWs and the electrodes is of great significance for the application of β-Ga2O3 based detectors.