am5b08382_si_001.pdf (387.83 kB)
Effect of SiO2 Spacer-Layer Thickness on Localized Surface Plasmon-Enhanced ZnO Nanorod Array LEDs
journal contribution
posted on 2016-01-27, 00:00 authored by Weizhen Liu, Haiyang Xu, Siyi Yan, Cen Zhang, Lingling Wang, Chunliang Wang, Liu Yang, Xinhua Wang, Lixia Zhang, Jiannong Wang, Yichun LiuLocalized surface plasmon (LSP)-enhanced
ultraviolet LEDs have been constructed via spin-coating Ag nanoparticles
onto ZnO/SiO2 core/shell nanorod array/p-GaN heterostructures.
Different from the previous reports where the dielectric spacer-layer
thickness was determined only through photoluminescence (PL) characterization,
the SiO2 shell thickness in this work is also optimized
by actual electroluminescence (EL) measurements to maximize the enhancement.
It is interesting to find that the enhancement ratios derived from
PL and EL measurements demonstrate different thickness dependences
on SiO2 shell: an optimal 3.5-fold PL enhancement was obtained
at the SiO2 thickness of 16 nm, while an “abnormal”
7-fold EL enhancement was achieved at the thickness of 12 nm. Time-resolved
spectroscopy studies, as well as theoretical estimations and numerical
simulations, reveal that the higher-ratio EL enhancement stems from
joint contributions, both internal-quantum-efficiency improvement
induced by exciton-LSP coupling and light-extraction-efficiency improvement
aroused by photon-LSP coupling.