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Spectrally Selective and Highly Sensitive UV Photodetection with UV‐A,C Band Specific Polarity Switching in Silver Plasmonic Nanoparticle Enhanced Gallium Oxide Thin‐Film
Author(s) -
Arora Kanika,
Singh Dhruv P.,
Fischer Peer,
Kumar Mukesh
Publication year - 2020
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.202000212
Subject(s) - materials science , responsivity , optoelectronics , photodetector , photocurrent , plasmon , photodetection , surface plasmon resonance , nanoparticle , thin film , band gap , quantum efficiency , silver nanoparticle , optics , nanotechnology , physics
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.