Surface plasmons on Ag clusters induced via ultrasonic and thermal treatments and the enhancement of Si nanocrystal light emission

• A facile method of producing Ag clusters on SiO2 with ultrasonic and thermal treatments is developed.
• This method is readily controllable in Ag cluster size and density and applicable.
• Localized surface plasmons generated on the Ag clusters enhance the photoluminescence of Si nanocrystals by a factor of 3.6.

Quartz substrates are ultrasonically irradiated within AgNO3 solution, followed by postannealing in nitrogen atmosphere at elevated temperatures (Ta׳s) between 200 and 800 °C. Ag clusters with sizes in the order of 102 nm appear on the SiO2 surfaces after the ultrasonic and thermal treatments. Absorption spectra induced by localized surface plasmons (LSPs) on Ag clusters are observed. The most prominent absorption occurs for Ta=400 °C. From Ta=200 to 400 °C, AgNO3 on SiO2 experiences thermal decomposition, Ag cluster formation and ripening. From Ta=600 to 800 °C, Ag oxide nano-rings form. Application of the LSPs to Si nanocrystal-doped SiO2 (Si-NC:SiO2) thin film yields an enhancement of photoluminescence (PL) of Si-NCs, with a maximal 3.6-fold enhancement obtained for Ta=400 °C. The PL enhancement is attributed to the LSP field coupling to the exciton dipole moment of Si-NC.

Ag clusters are readily formed on SiO2 via ultrasonic and thermal treatments, on which, photo-induced surface plasmons enhance the photoluminescence of Si nanocrystals inside SiO2.Figure optionsDownload as PowerPoint slide