The plasmonic Dicke effect means a cooperative emission mechanism of multiple light emitters when they are simultaneously coupled with the same surface plasmon (SP) mode of a metal nanostructure to achieve a higher collective emission efficiency. Here, we compare the enhancements of emission efficiency among a series of SP-coupled InGaN/GaN quantum-well (QW) structures of different QW period numbers to show an emission behavior consistent with the plasmonic Dicke effect. The relative enhancement of overall emission efficiency increases with QW period number until it reaches a critical value, beyond which the enhancement starts to decrease. This critical QW period number corresponds to the effective depth range of the plasmonic Dicke effect in a multiple-QW system. It also represents an optimized QW structure for maximizing the SP coupling effect. Internal quantum efficiency and time-resolved photoluminescence are measured for comparing the enhanced emission efficiencies of blue and green QW structures with different QW period numbers through SP coupling induced by surface Ag nanoparticles.

By forming nanodisk (ND) structures on a blue-emitting InGaN/GaN quantum-well (QW) template, the QWs become close to the red-emitting quantum dots (QDs) and Ag nanoparticles (NPs) attached onto the sidewalls of the NDs such that Förster resonance energy transfer (FRET) and surface plasmon (SP) coupling can occur to enhance the efficiency of blue-to-red color conversion. With a larger ND height, more QWs are exposed to open air on the sidewall for more QD/Ag NP attachment through QD self-assembly and Ag NP drop casting such that the FRET and SP coupling effects, and hence the color conversion efficiency can be enhanced. A stronger FRET process leads to a longer QD photoluminescence (PL) decay time and a shorter QW PL decay time. It is shown that SP coupling can enhance the FRET efficiency.

Based on the generation and transportation of hot electrons and the diffusion-limited aggregation of Ag + ions induced by the surface plasmon resonance of surface Ag nanoparticles (NPs) with ambient moisture, we develop a new mechanism for fabricating a surface Ag nanonetwork (NNW) structure on a slightly conductive template through Ag NP reorganization and AgO x formation. Such an extended NNW structure consists of distributed Ag NPs covered and connected by AgO x to form a highly transparent conductive network. Its sheet resistance is as low as ∼140 Ω/square while its transmittance lies between 80 and 90%. The process of diffusion-limited aggregation is regulated by electrostatic induction between diffuse Ag + ions in a thin surface water layer condensed from moisture and the sharp tips of an NNW structure during its formation. Oxygen atoms can be dissociated from AgO x when a post-thermal treatment at a temperature higher than 412 °C is applied, leaving behind an Ag thin layer, which still connects the remaining Ag NPs to form a different conductive network of ∼240 Ω/square in sheet resistance. Such an NNW structure can stand an elevated temperature up to ∼400 °C and is thermally stable. It can extend the transparent spectrum into ultraviolet and near-infrared ranges and can be applied to touch-panel displays, ultraviolet light-emitting diodes, and flexible optoelectronics devices.

An AlGaN/GaN multi-shell structure on a GaN nanorod (NR) is formed by using the selfcatalytic pulsed growth process of metalorganic chemical vapor deposition with Ga and Al/N supplies in the first and second half-cycles, respectively. With Al supply, a thin AlGaN layer is precipitated near the end of a growth cycle to form the AlGaN/GaN structure. Because of the lower chemical potential for GaN nucleation, when compared with AlN, a GaN layer is first deposited in a growth cycle. AlGaN is not precipitated until the AlN nucleation probability becomes higher when the catalytic Ga droplet is almost exhausted. Because the Al adatoms on the NR sidewalls hinder the upward migration of Ga adatoms for contributing to the Ga droplet at the NR top, the size of the Ga droplet decreases along growth cycle leading to the decrease of GaN layer thickness at the top until a steady state is reached. In this process, the slant facet of an NR changes from the (1-102)-plane into (1-101)-plane. To interpret the observed growth behaviors, formulations are derived for theoretically modeling the AlN nucleation probability, NR height increment in each growth cycle, and the time of exhausting the Ga droplet in a cycle.

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