Synergy Between PtNPs-Induced Plasmonic Effect and Localized Depletion Layer for Enhancing Performance of Ga₂O₃-Based Heterojunction Solar-Blind Photodetectors

Solar-blind photodetectors that are exclusively sensitive to deep ultraviolet (UV) have garnered increasing interest due to their potential applications. In this work, self-powered solar-blind heterojunction photodetectors consisting of Pt nanoparticles (PtNPs)-decorated a Ga2O3 microwire (PtNPs@Ga2O3 MW) and p-type GaAs substrate are proposed. The PtNPs@Ga2O3/GaAs heterojunction photodetector demonstrates an ultrahigh responsivity of 160 mA/W, a high specific detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.1\times 10^{{12}}$ </tex-math></inline-formula> Jones and an ultrafast rise/decay time (183/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$450~\mu $ </tex-math></inline-formula>s) upon 245-nm light illumination at zero bias. The physical mechanism of the device’s performance was comprehensively analyzed by the finite difference time-domain (FDTD) and the finite element method calculation. On the one hand, PtNPs-induced near-field enhancement combined with prominent scattering and absorption characteristics in solar-blind region enables to boost the generation of carriers and photocurrent. One the other hand, the localized depletion layer at PtNPs/Ga2O3 interface accelerates the separation of nonequilibrium carriers, which is further confirmed by transient photoelectric response. Our findings give a deeper insight into the influence of PtNPs on deep-UV photoresponse and its coupling mechanism with Ga2O3, providing a scheme to develop high-performance self-powered solar-blind photodetectors.