Characterization of high quality ZnO nanowire surface plasmon resonance sensors on Si substrate with perforated aluminum cylindrical micropillar arrays

Abstract

Zinc oxide (ZnO) has attracted intensive research effort in recent years, due to its unique properties and versatile applications. The optical characterization of high quality ZnO nanowire surface plasmon resonance (SPR) sensors with perforated cylindrical micropillar arrays is investigated. In-doped ZnO nanowires coupled surface plasmon resonance, from PL spectra, it is found that the In-doped ZnO nanowires have a blue emission at 425 nm, which resulted from the ZnO band-to-band transition with SPR coupling effect. Prior to the arrays of samples were annealed, a broad green emission centered at 500 nm was observed, which is attributed to ZnO native point defects. The relatively strong green band emission results from the radial recombination that arises from the ionized oxygen vacancy. Compare the p-ZnO on Si substrate, the enhancement of PL intensity for p-ZnO with deposited Al pattern film can be attributed to strong coupling interaction with SPR and exciton over a broad temperature range. Electron-hole pairs excited within In-doped ZnO film couple to SP at the metal/semiconductor interface when the energies of excitons in ZnO and the ones of the metal SP energy are resemble. It has found that a unique emission peak on PL spectra due to the SPR effect within In-ZnO interface. These experimental results indicate that a perforated Al array can significantly affect carrier confinement and enhance the quantum efficiency of In-doped ZnO/Al heterostructures due to the interaction of SPR coupling between ZnO nanowire and Al film. It is demonstrated that SPR sensors may attain higher sensitivity with ZnO sensing nanostructures.