Abstract
We investigated plasmon-assisted enhancement of emission from silicon nanoparticles (ncs-Si) embedded into porous SiO x matrix in the 500- to 820-nm wavelength range. In the presence in the near-surface region of gold nanoisland film, ncs-Si exhibited up to twofold luminescence enhancement at emission frequencies that correspond to the plasmon resonance frequency of Au nanoparticles. Enhancement of the photoluminescence (PL) intensity was attributed to coupling with the localized surface plasmons (LSPs) excited in Au nanoparticles and to increase in the radiative decay rate of ncs-Si. It has been shown that spontaneous emission decay rate of ncs-Si modified by thin Au film over the wide emission spectral range was accelerated. The emission decay rate distribution was determined by fitting the experimental decay curves to the stretched exponential model. The observed increase of the PL decay rate distribution width for the Au-coated nc-Si-SiO x sample in comparison with the uncoated one was explained by fluctuations in the surface-plasmon excitation rate.PACS78. 67. Bf; 78.55.-m
Highlights
Enhancement of the intensity and emission rate of quantum emitters is of significant interest during the past decade
Close peak positions of the ncs-Si emission and absorption of Au nanoparticles indicate that excitons generated in ncs-Si could effectively couple to electron vibrations at the surface of Au nanoparticles because the emission frequency is matched to the plasmon resonance one
It has been shown that the spontaneous emission decay rate of the excited ncs-Si in the sample coated by Au nanoislands was accelerated
Summary
Enhancement of the intensity and emission rate of quantum emitters is of significant interest during the past decade. One of the approaches to enhance luminescence efficiency of low-dimensional materials is to realize the coupling of electronic excitation in quantum dots and wells with the surface plasmons (SPs) supported by metal nanostructures. When a planar metal film is placed above a luminescent material, the emission decay rate of it increases due to excitation of the propagating mode surface plasmons [1,2]. Surface plasmon excitations in bounded geometries such as nanostructured metal particles are localized surface plasmons (LSPs). The resonant excitation of LSPs on the surface of nanostructured metallic particles by an incident light causes strong light scattering and absorption and enhanced structures resulting from the coupling between ncs-Si and LSPs excited in Au nanoparticles
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