Spectrally Selective and Highly Sensitive UV Photodetection with UV‐A,C Band Specific Polarity Switching in Silver Plasmonic Nanoparticle Enhanced Gallium Oxide Thin‐Film
K.K. Arora, Dhruv Singh, Peer Fischer, Mukesh Kumar
Abstract
Abstract Traditional photodetectors generally show a unipolar photocurrent response when illuminated with light of wavelength equal or shorter than the optical bandgap. Here, it is reported that a thin film of gallium oxide (GO) decorated with plasmonic nanoparticles, surprisingly, exhibits a change in the polarity of the photocurrent for different UV bands. Silver nanoparticles (Ag NPs) are vacuum‐deposited onto β‐Ga 2 O 3 and the AgNP@GO thin films show a record responsivity of 250 A W −1 , which significantly outperforms bare GO planar photodetectors. The photoresponsivity reverses sign from +157 µA W −1 in the UV‐C band under unbiased operation to −353 µA W −1 in the UV‐A band. The current reversal is rationalized by considering the charge dynamics stemming from hot electrons generated when the incident light excites a local surface plasmon resonance in the Ag nanoparticles. The Ag nanoparticles improve the external quantum efficiency and detectivity by nearly one order of magnitude with high values of 1.2 × 10 5 and 3.4 × 10 14 Jones, respectively. This plasmon‐enhanced solar blind GO detector allows UV regions to be spectrally distinguished, which is useful for the development of sensitive dynamic imaging photodetectors.