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

The authors report an indium tin oxide (ITO) decorated solar-blind deep ultraviolet photodetectors (PDs) based on high quality beta-Ga2O3 single crystal microwires (MWs). An ultrahigh photo-to-dark current (I (photo)/I (dark)) ratio similar to 10(7) of the PDs has been realized. Compared with In/beta-Ga2O3/In metal-semiconductor-mental (MSM) PD, the device with ITO as the interlayers between In and beta-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 x 10(-13) A and a photocurrent up to 1.0 x 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 x 10(5), a detectivity D* of 1.23 x 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/beta-Ga2O3 interfaces and the reduced carrier trapping behavior induced by the beta-Ga2O3 surface states. The introduction of ITO between MWs and the electrodes is of great significance for the application of beta-Ga2O3 based detectors.