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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

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Fischer,  Peer
Optical Nanoscopy, Max Planck Institute for Medical Research, Max Planck Society;

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Citation

Arora, K., Singh, D. P., Fischer, P., & Kumar, M. (2020). Spectrally selective and highly-sensitive UV photodetection with UV-A, C band specific polarity switching in silver plasmonic nanoparticle enhanced gallium oxide thin-film. Advanced Optical Materials, 8(16): 2000212, pp. 1-9. doi:10.1002/adom.202000212.


Cite as: https://hdl.handle.net/21.11116/0000-000B-345A-6
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-Ga2O3 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 × 105 and 3.4 × 1014 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.