Enhancement of photoluminescence from excitons in silicon nanocrystals via coupling to surface plasmon polaritons

Abstract

The enhancement of photoluminescence (PL) is demonstrated from silicon nanocrystals (Si-ncs) by strong coupling of excitons to surface plasmon polaritons (SPPs) supported by a Au thin film. SPPs excited via excitons in Si-ncs were Bragg scattered to photons by one- or two-dimensional gratings, and strong and directional PL was obtained. From the angular dependence of PL spectra, dispersion relations of electromagnetic modes involved in the light emission process were obtained. The overall agreement between experimentally obtained and theoretically calculated dispersion relations confirmed that the strong and directional PL is mediated by SPPs. The PL decay rate of Si-ncs increased by placing a Au thin film on top and the wavelength dependence of the rate enhancement agreed well with that of the calculated SPP excitation rate. This suggests that the observed PL enhancement is due to efficient energy transfer from excitons to SPPs followed by efficient scattering of SPPs to photons, resulting in the enhancement of luminescence quantum efficiency.

Plasmonic band gap structures for surface-enhanced Raman scattering

“…Photoluminescence spectrum mimics the features of the reflection spectrum both in wavelength and the width of the peaks. The enhancement mechanism is based on the excitation of SPPs on the metal surface [29][30][31]. Emitted photon couples to the SPPs through higher grating components (Λ 1 =500 nm) or near field effects.…”

Plasmonic engineering of spontaneous emission from silicon nanocrystals

“…Pioneering work has been performed by Biteen et al with nanoporous gold15, evidencing a four-fold enhancement of SiNCs' photoluminescence. Further studies have dealt with the coupling between SiNCs and plasmonics nanostructures such as Ag nanodisks16, metallic gratings171819, and Ag nanotriangles20. However, in most of these works, information obtained on coupling was limited by the contribution of uncoupled SiNCs, which were not located at a controllable distance of the metallic particles.…”

Surface plasmon resonance sensor based at metallic subwavelength structures

“…Many scientists studies the optical properties of metallic nanostructures and the SPPs' excitation at metal film surface, which have extensive application in the light beaming [7][8][9], localized field intensity enhancement [10,11], Raman scattering enhancement [12,13], biochemical sensor device [14,15] and photonics, nanophotonics circuit construction [16][17][18][19] and so on. Sensor based surface plasmon polaritons have been extensively studied experimentally [20][21][22] and theoretically [23][24][25] and the refractive index sensitivity is better.…”