Au decorated ZnO nanostructures for enhanced visible emission and memory applications

Abstract

Metal/semiconductor nanocomposites present the most versatile way to tune the optical and electrical properties of semiconductors at the nanometer scale. In the present study, Au/ZnO contacts were investigated for their potential applications in optoelectronic devices. There is general agreement that the resonant excitation of surface plasmons (SP) of metal nanoparticles (NP) can couple with the excitons of semiconductors and tune their optical emissions. In this work, the SP and exciton coupling is thoroughly examined using temperature dependent photoluminescence (PL) spectroscopy and Raman spectroscopy in the Au-NPs coated ZnO nanowires. Peculiar to the conventional optical response of Au/ZnO nanostructures at room temperature, PL measurements manifest the suppression of the band edge emissions and enhanced deep level emissions after Au-NPs coating. Raman spectroscopy showed the surface-enhanced Raman scattering (SERS) effect due to field enhancement of the incident light by the SP thus demonstrating potential in ultrasensitive sensing applications. Also, ZnO memristors were fabricated with Au electrodes that exhibited high endurance and longtime retentive bipolar resistive switching characteristics with low SET/RESET voltages. Altogether, present results demonstrate that Au/ZnO composites hold promise for plasmonic based nanoelectronics for memory and neuromorphic applications.