Enhanced Responsivity of Pd Nanoparticle-Decorated β-Ga₂O₃ Photodiodes via Localized Surface Plasmon Resonance

Localized surface plasmon resonance (LSPR) is an effective method to enhance the detective performance of photodetectors across ultraviolet to infrared regions. In this work, Schottky photodiodes (SPDs) for solar-blind detection have been fabricated with ultrawide bandgap β-Ga₂O₃ grown on off-axis sapphire substrates. Palladium nanoparticles (Pd NPs) are used to modify the β-Ga₂O₃ films via a handy method of solid-state dewetting, for which the particle size ranges from 55 to 180 nm by modulating the thickness of as-deposited Pd films. As a result, optoelectronic characteristics of the device with β-Ga₂O₃ modified by Pd NPs with 115 nm diameter demonstrate an optimal responsivity of 827 A W⁻¹ and external quantum efficiency of 4 × 10⁵%, which are three times higher than the pristine device. This is attributed to the enhanced mechanism of Pd NPs via LSPR, which provides a viable pathway toward high performance β-Ga₂O₃ solar-blind photodetectors.