Insight of dipole surface plasmon mediated optoelectronic property tuning of ZnO thin films using Au

Surface plasmon mediated photoluminescence (PL) studies of ZnO, ZnO/Au, ZnO/Au/ZnO and Au/ZnO films have been investigated. An enhancement of UV and visible light emission has been observed in ZnO/Au and ZnO/Au/ZnO films, compared to that of ZnO thin films, while for Au/ZnO films quenching of PL intensity was observed. Excitation intensity (EI) dependent PL spectra have shown dominance of horizontal dipole surface plasmon mode for ZnO/Au/ZnO, ZnO/Au samples, which led enhanced greenish-yellow and orange emissions respectively. Moreover, confocal laser scanning microscope measurements and diffuse reflectance spectroscopy were conducted to investigate the mechanism behind the variations and involvement of Urbach tail. UV and visible region absorption were selectively enhanced by varying the Au and ZnO configuration and can be assigned to the interaction of the dipole surface plasmon resonance with localized trapping levels and phonon subsystem. The excellent photoluminescence performance has immense potential for ZnO thin film based optoelectronic devices. (C) 2016 Elsevier B.V. All rights reserved.