The metallic-structure dependent localized surface plasmons (LSPs) coupling behaviors with InGaN QWs in a green LED epitaxial wafer are investigated by optical transmission, scanning electron microscopy (SEM) and photoluminescence (PL) measurements. Ag nanoparticles (NPs) are formed by thermal annealing Ag layer on the green LED wafer. SEM images show that for higher annealing temperature and/or thicker deposited Ag layer, larger Ag NPs can be produced, leading to the redshift of absorption peaks in the transmission spectra. Time resolved PL (TRPL) measurements indicate when LSP-MQW coupling occurs, PL decay rate is greatly enhanced especially at the resonant wavelength 560 nm. However, the PL intensity is suppressed by 3.5 folds compared to the bare LED. The resonant absorption and PL suppression are simulated by three dimension finite-difference-time-domain (FDTD), which suggests that Ag particle with smaller size and lower height lead to the larger dissipation of LSP.
InGaN/GaN nanorod light-emitting diode (LED) arrays were fabricated using nanoimprint and reactive ion etching. The diameters of the nanorods range from 120 to 300 nm. The integral photoluminescence (PL) intensity for 120 nm nanorod LED array is enhanced as 13 times compared to that of the planar one. In angular-resolved PL (ARPL) measurements, there are some strong lobes as resonant regime appeared in the far-field radiation patterns of small size nanorod array, in which the PL spectra are sharp and intense. The PL lifetime for resonant regime is 0.088 ns, which is 40 % lower than that of non-resonant regime for 120 nm nanorod LED array. At last, three dimension finite difference time domain (FDTD) simulation is performed. The effects of guided modes coupling in nanocavity and extraction by photonic crystals are explored.
In this work, the coupling behavior of multiple dipoles and localized surface plasmons (LSPs) in Ag nanoparticle arrays is explored based on experimental results and 3D finite difference time domain (FDTD) simulations. The Ag nanoparticles (NPs) located inside the hexagonal photonic crystal (PhC) array holes are embedded in a green lightemitting diode (LED), which enhances emission efficiency significantly. In the simulation of the 3D FDTD, five spaced x-polarized dipoles are approximated as five quantum wells. The internal quantum efficiency (IQE) and light extraction efficiency (LEE) of the LSP-coupled LED are deduced respectively from the original IQE of the bare LED and the FDTD simulation results. Besides, the dynamic LSP-dipole coupling behavior is also explored considering the interaction of the five dipoles and their feedback effect to LSP, which lead to the magnification of the LSP-dipole coupling enhancement effect and the reduction of energy dissipation in Ag NPs.
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