Band-edge emission enhancement in sputtered ZnO thin films with ultraviolet surface lattice resonances

TL;DR

This study demonstrates that aluminum nanoparticle arrays can enhance the ultraviolet photoluminescence of ZnO thin films by tuning surface lattice resonances, achieving up to threefold emission increase through experimental and numerical analysis.

Contribution

It introduces a novel solid-state UV emitter using ZnO and Al nanorod arrays that harness surface lattice resonances for enhanced photoluminescence.

Findings

NBE emission increased up to 3 times with Al nanorod arrays

Surface lattice resonances outperform localized surface plasmon resonances in enhancement

Tunable SLRs achieved by adjusting array period and nanorod dimensions

Abstract

Metallic nanostructures acting as optical nanoantennas can significantly enhance the photoluminescence (PL) of nearby emitters. Albeit luminescence enhancement factors of several orders of magnitude have been reported for quantum dots or molecules, in the case of bulk emitters the magnitude of the plasmonic enhancement is strongly hindered by the weak spatial overlap between the active medium and the electromagnetic modes of the nanoantenna. Here, we propose a solid-state ultraviolet emitter based on a thin film of zinc oxide (ZnO) coupled with an array of aluminum (Al) nanoparticles. The Al nanorod array is designed to sustain surface lattice resonances (SLRs) in the near ultraviolet, which are hybrid modes exhibiting a Fano-like lineshape with narrowed linewidth relatively to the non-hybridized plasmonic modes. By changing both the period of the array and the dimensions of the nanorods, the generated SLR is tuned either to the near band-edge (NBE) emission of ZnO or to the excitation wavelength. We experimentally demonstrate that NBE emission can be increased up to a factor of 3 compared to bare ZnO. The underlying PL enhancement mechanisms are experimentally investigated and compared with numerical simulations. We also demonstrate that SLRs are more efficient for the ZnO luminescence enhancement compared to localized surface plasmon resonances.