Interfacial engineering boosted narrow-band ultraviolet LED based on n-PtNPs@ZnO:Ga microwire/AlN/p-GaN heterojunction

Abstract

Low-dimensional ZnO micro/nanocrystals having high optical gain, self-constructed microcavity and large-bandgap, is the largest potential constituent for constructing droop-free and high-brightness ultraviolet light sources. In this study, we reported a workable scheme to construct high-monochromatic ultraviolet electroluminescence devices including a Ga-doped ZnO microwire decoated with platinum nanoparticles (PtNPs@ZnO:Ga MW), an AlN electron blocking layer and p-GaN layer substrate. The device exhibits a robust narrow-band ultraviolet electroluminescence peaking at around 374.8 nm and a narrowing bandwidth ∼ 13.5 nm. The electroluminescence profile is comparable with photoluminescence spectrum of ZnO:Ga MW. The device properties can be interpreted by the working mechanism of plasmonic effects, heterojunction interface engineering and optimization strategies. The AlN intermediate layer appeared in the optimized device enables effectively to tune the paths of current traveling and carrier recombination, yielding the band-edge luminescence of ZnO:Ga MW. As the device is further modified using PtNPs with desired plasmons, the optimization of heterojunction interface is significantly boosted, like the observable enhancement of holes injection efficiency, electroluminescence efficiency and interface contact, etc. Thereby, the boosted band-edge luminescence of ZnO:Ga MW can contribute to the well-being of the enhanced ultraviolet electroluminescence in our constructed LED devices. The findings are looking forward to bringing new opportunities toward the implementation of ultra-bright and high-efficiency narrow-band ultraviolet light sources, especially for the achievement of electrically-pumped microlaser devices.

Keywords

• Narrow-band ultraviolet LED
• ZnO:Ga microwires
• AlN buffer layer
• PtNPs plasmons
• Microcavity effect
• Interface engineering