Extra green light induced ZnO ultraviolet lasing enhancement assisted by Au surface plasmons

Abstract

We observed the dramatic enhancement of the intrinsic spontaneous and stimulated emission as well as the ensuing suppression of defect-related green emission in Au-decorated ZnO microrods. A series of spectral experiments and theoretical analysis demonstrated an electron transfer assisted process by surface plasmon (SP) resonant coupling between the Au nanoparticles and ZnO. The mechanism indicates an approach to enhance the UV emission of ZnO through an extra excitation of visible light similar to that for the defect emission of ZnO. Based on the coupling mechanism, the externally enhanced ultraviolet lasing was further improved from 1.5 to 2.8-fold by adjusting the pumping power of the green light intensity in the Au/ZnO hybrid cavity. This research not only further confirms the SPR-assisted electron transfer process but also offers an approach to improve the intrinsic UV emission even for heavily-defected ZnO through visible light excitation via a nonlinear process.

Hybrid quadrupole plasmon induced spectrally pure ultraviolet emission from a single AgNPs@ZnO:Ga microwire based heterojunction diode

“…Thus, the PL emission enhancement of a single ZnO:Ga MW with Ag nanoparticle decoration cannot be attributed to resonant coupling between ZnO:Ga excitons and AgNPs plasmons at the interface. 21,22,55 When the output radiation from the heterojunction LED is absorbed by the deposited Ag nanoparticles, hybrid quadrupole plasmons can be excited. Aer excitation, nonradiative decay can occur through intraband excitations within the conduction band or through interband excitations, leading to transitions between the conduction band and other bands.…”

“…[17][18][19][20][21] By incorporating noble metal nanostructures, such as Ag nanoparticles, the localized surface plasmon resonance effect has been considered to be an efficient strategy to enhance the luminous efficiency of light-emitting materials and devices, with ZnO micro/nanostructures serving as active layers. [22][23][24] Due to the small sizes of the plasmonic nanostructures, the optical response of the spherical nanostructures embedded in the dielectric materials exhibits dipole surface plasmon resonance modes, which result in strong attenuation of incident light. Nevertheless, owing to serious metallic losses arising from interband electronic transitions, metal plasmons are trapped in the visible spectral band.…”

“…The spectral linewidths of the EL emission spectra were much wider than that of the PL spectrum of the single MW. 18,22,34,65 The detailed EL emission characteristics can be seen in Fig. S3 in the ESI.…”

Lasing mode regulation in zinc oxide microcavity

“…ZnO导带底, 电子从SPR态转移至导带从而使得导带电 图 7 (网络版彩色)金属等离激元增强的ZnO微腔激光. (a) 在不同激光激励下微腔的激光光谱图, 插图为325和532 nm波长的两束光激发Au/ ZnO微米棒示意图 [83] ; Copyright © 2018 Royal Society of Chemistry. (b) Au/ZnO微腔中能量耦合和等离子体辅助电子转移的示意图 [82] ; (c) Pt NPs 修饰前后ZnO微梳的激射光谱; (d) Pt/ZnO微腔中能量耦合和电子转移的示意图 [58] .…”

“…(a) Lasing spectra with the different excitation in Au/ZnO microrod. The inserted images the schematic diagram of Au/ZnO microrod witha 325 and 532 nm laser excitation [83] . Copyright © 2018 Royal Society of Chemistry.…”