Broad Range (254–302 nm) and High Performance Ga2O3:SnO2 Based Deep UV Photodetector

Abstract

The harmful UV radiation leaking out of the ozone hole can have a detrimental effect on mother nature. To monitor any UV rays leaking out of the ozone hole requires an electronic device such as deep UV photodetectors. In this context, Sn-doped Ga₂O₃ incorporated with SnO₂ nanostructures has been grown on a c-plane sapphire substrate using low-pressure chemical vapor deposition (LPCVD) followed by the fabrication of metal-semiconductor-metal (MSM) based deep ultraviolet (UV) photodetector (PD) using Pt as electrodes with interdigitated geometry. The PD possesses a low dark current of 21 nA even at 50 V bias with a very high photo-to-dark current ratio of 9 × 10⁴ and exceptionally large responsivity of 1532 and 262 A/W under 254 nm and 302 nm UV-illumination respectively. Consequently, an extremely high detectivity of 1.7 × 10¹⁵ Jones and external quantum efficiency of 7.4 × 10⁵% has been recorded under 254 nm illumination with a fast fall time of 0.2 sec. The PD works well in UV-B range with high responsivity and is attributed to the long wavelength absorption by the SnO₂ nanostructures accompanied by a charge transfer from SnO₂ to the Ga₂O₃ layer. The high gain has been attributed to the photoconductive gain due to interface trapped charges and self-trapped holes, along with light trapping on the textured Ga₂O₃ surface.