An MSM photodetector based on an InGaO/TiO2 heterojunction for high-performance UV detection

Abstract

As typical metal–oxide wide bandgap semiconductor devices, ultraviolet (UV) photodetectors (PDs) based on TiO2 have encountered challenges related to high dark current and low photo-to-dark suppression ratio. In this study, indium (In) was doped into Ga2O3 to create the compound InGaO (IGO). Subsequently, IGO was combined with TiO2 to fabricate IGO/TiO2 heterojunction (ITH) MSM UVPDs. The built-in electric field constructed at the contact interface is capable of depleting the majority carriers in dark and limiting the dark current. The Au interdigital electrodes and the IGO film of the top layer will form an Ohmic contact without the carrier transport barrier to construct a photoconductive device with high photo currents. The results show that the ITH UVPDs exhibit a notable photo current of 1.21 mA and a low dark current of 0.29 nA, leading to an ultrahigh photo-to-dark current ratio of 6 orders of magnitude (4.17 × 106). Additionally, the UVPDs demonstrate a significant responsivity (R) of 1.16 × 104 A/W and a remarkable detectivity (D*) of 7.34 × 1015 Jones under 290 nm UV illumination at 5 V bias. This study provides a potential method for fabricating high-performance UVPDs.