Abstract

A dielectric microsphere is a multifunctional platform to manipulate light in microscale by nanofocusing, optical whispering gallery resonance, and unidirectional antenna. Dielectric microsphere arrays (MSAs) have demonstrated the capability for photoluminescence (PL) and Raman enhancement without plasmonics. In this work, we investigate the effects of excitation power, tilting angle, and temperature on PL enhancement of high-quality zinc oxide (ZnO) single-crystal capping with fused silica MSAs. The microsphere diameter is optimized to 3.5–5.5 μm, achieving the maximum UV-PL enhancement ratio of intensity (ERI) up to tenfold by strong focusing and unidirectional antenna effects. Under the excitation power $<0.2\mathrm{mW}$, the incident light focused by the MSA increases the localized exciton state density for a higher ERI of $\sim 15$-fold. The angle-sensitive PL intensity from the MSA enhancer provides a simple approach achieving unidirectional UV emission from planar ZnO. The 16-fold enhancement for UV-PL near 130°C is also demonstrated, for the first time, owing to thermal ionization of hydrogen-related donor that increases free-exciton concentration. The high temperature stability and reproducibility of PL enhancement up to 400°C promote the nonplasmonic MSAs superior to surface plasmon-related metal nanostructures for ZnO-based highly efficient luminescence and highly sensitive photon detection above room temperature.

© 2018 Optical Society of America

Sandwich-structure-modulated photoluminescence enhancement of wide bandgap semiconductors capping with dielectric microsphere arrays

Lixue Yang, Yinzhou Yan, Qiang Wang, Yong Zeng, Feifei Liu, Lin Li, Yan Zhao, and Yijian Jiang
Opt. Express 25(6) 6000-6014 (2017)

Influence of Al capping on the photoluminescence of ZnO

Xi Ding, Yanjun Fang, Ming Zhao, Wei Wang, Jian Sha, and Yewu Wang
Opt. Mater. Express 7(6) 1898-1905 (2017)

Synergistically enhanced ultraviolet emission of Yb doped ZnO films by using a capping of ultrathin Al and SiO₂ microspheres

L. Zhang, C. L. Heng, X. Wang, W. Y. Su, and T. G. Finstad
Opt. Express 30(21) 38167-38177 (2022)

Ultraviolet luminescence enhancement of planar wide bandgap semiconductor film by a hybrid microsphere cavity/dual metallic nanoparticles sandwich structure

Yujie Zhang, Yinzhou Yan, Lixue Yang, Cheng Xing, Yong Zeng, Yan Zhao, and Yijian Jiang
Opt. Express 27(11) 15399-15412 (2019)

Ten-fold enhancement of ZnO thin film ultraviolet-luminescence by dielectric microsphere arrays

Yinzhou Yan, Yong Zeng, Yan Wu, Yan Zhao, Lingfei Ji, Yijian Jiang, and Lin Li
Opt. Express 22(19) 23552-23564 (2014)