Charge transfer plasmon coupled surface photosensing in ZnO nanorods–Au array hetero-nanostructures

Abstract

Well-aligned zinc oxide nanorods (ZnO NRs) array have been grown by wet chemical method on seeded substrates at low temperature. Gold nanosheet has been deposited by DC magnetron sputtering on the surrounding of the ZnO NRs array at glancing angle, thus creating a three-dimensionally (3D) plasmonic hetero-nanostructure (HNS). The localized surface plasmon resonance (LSPR) is tuned and blue-shifted as the thickness of the gold nanosheet increased. The efficient surface plasmon (SP) excitation, and charge transfer plasmon through tunneling transport and junction conductance elevates the locally electromagnetic field and subsequently enhances surface Raman scattering in ZnO NRs-Au array HNS. An enhanced factor (EF) of 500 can be obtained for the surface enhancement Raman scattering (SERS) response for ZnO NRs-Au array HNS. Photoluminescence spectrum shows Au- mediated blue emission enhancement. The ZnO NRs–Au HNSs show high nonlinear refractive index and nonlinear optical absorption coefficient around 10−5 cm2/W and 1 cm/W, respectively. The ZnO NRs-Au array HNS can provide the figures of merit w = 209.83 and t = 0.59 for the optical switching devices. Photosensitivity and photocatalytic activity are elevated in ZnO NRs-Au array HNS. The ZnO NRs-Au array HNS shows maximal photocurrent enhancement of 69.38% in comparison to the bare ZnO NRs array.