High-responsivity photoelectrochemical ultraviolet photodetector based on SnO2 nanosheets-Ga2O3

Abstract Tin oxide (SnO 2 ) has garnered significant attention for its high spectral selectivity when used as an ultraviolet photodetector (PD). In this study, SnO 2 nanosheets (NSs) were synthesized via a hydrothermal method, followed by spin-coating a layer of Ga 2 O 3 thin film to construct a heterojunction photoelectrochemical ultraviolet PD (PEC UV PD). Initially, we investigated the effect of precursor composition on the properties of the Ga 2 O 3 thin films. It was observed that the thickness of the films increased with higher precursor concentrations, while the optical bandgap decreased. Based on these findings, we successfully fabricated the SnO 2 NSs-Ga 2 O 3 PEC UV PD. Electrochemical analysis revealed that as the precursor concentration used for spin-coating Ga 2 O 3 increased, the device’s responsivity and detectivity initially increased and then decreased. After optimization, the device prepared with a 0.2 M Ga(NO 3 ) 3 solution spin-coated on SnO 2 exhibited excellent spectral selectivity ( R 265nm / R 420nm ∼ 4472), a responsivity of 4.86 mA W −1 , and a detectivity of 2.72 × 10 9 Jones. This study demonstrates that coating Ga 2 O 3 is an effective approach to constructing high-performance SnO 2 -based UV PDs.