Localized surface plasmon enhanced Ga₂O₃ solar blind photodetectors

Abstract

Enhancement in the light interaction between plasmonic nanoparticles (NPs) and semiconductors is a promising way to enhance the performance of optoelectronic devices beyond the conventional limit. In this work, we demonstrated improved performance of Ga 2 O 3 solar-blind photodetectors (PDs) by the decoration of Rh metal nanoparticles (NPs). Integrated with Rh NPs on oxidized Ga 2 O 3 surface, the resultant device exhibits a reduced dark current of about 10 pA, an obvious enhancement in peak responsivity of 2.76 A/W at around 255 nm, relatively fast response and recovery decay times of 1.76 ms/0.80 ms and thus a high detectivity of ∼10 13 Jones. Simultaneously, the photoresponsivity above 290 nm wavelength decreases significantly with improved rejection ratio between ultraviolet A (UVA) and ultraviolet B (UVB) regions, indicative of enhanced wavelength detecting selectivity. The plasmonic resonance features observed in transmittance spectra are consistent with the finite difference time-domain (FDTD) calculations. This agreement indicates that the enhanced electric field strength induced by the localized surface plasmon resonance is responsible for the enhanced absorption and photoresponsivity. The formed localized Schottky barrier at the interface of Rh/Ga 2 O 3 will deplete the carriers at the Ga 2 O 3 surface and lead to the remarkable reduced dark current and thus improve the detectivity. These findings provide direct evidence for Rh plasmonic enhancement in solar-blind spectral region, offering an alternative pathway for the rational design of high-performance solar-blind PDs.