Effect of SiO2 Spacer-Layer Thickness on Localized Surface Plasmon-Enhanced ZnO Nanorod Array LEDs

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• 作者：Weizhen Liu ; Haiyang Xu ; Siyi Yan ; Cen Zhang ; Lingling Wang ; Chunliang Wang ; Liu Yang ; Xinhua Wang ; Lixia Zhang ; Jiannong Wang ; Yichun Liu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：January 27, 2016
• 年：2016
• 卷：8
• 期：3
• 页码：1653-1660
• 全文大小：551K
• ISSN：1944-8252

文摘

Localized 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.