Target swapping in PLD: An efficient approach for CdS/SiO2 and CdS:Ag(1%)/SiO2 nanocomposite thin films with enhanced luminescent properties

Abstract

A novel synthesis method for luminescent and by-products (like CdO) free CdS/SiO2 and CdS:Ag(1%)/SiO2 (i.e. 1%Ag doped CdS/SiO2) nanocomposite thin films at room temperature by pulsed laser deposition is reported. Targets of CdS, CdS:Ag(1%) and SiO2 are used to deposit CdS/SiO2 and CdS:Ag(1%)/SiO2 nanocomposite thin films by swapping them at a frequency ratio of 2:8 laser pulses/sec. X-ray photoelectron spectroscopy analysis ensures the ratio of CdS to SiO2 in nanocomposite as 21:79 which is nearly same as the ratio of incident pulses/sec (i.e. 2:8) on the two targets. Transmission electron micrographs visualize the formation of CdS/ CdS:Ag(1%) nanocrystals in nanocomposite systems after annealing at 500 °C. Highly intense and broad red emission is achieved from CdS/SiO2 and CdS:Ag(1%)/SiO2 nanocomposites. The efficiencies of emission from pristine CdS:SiO2 and CdS:Ag(1%)/SiO2 nanocomposites are found to be enhanced by approximately two times as compared to sole nanocrystalline CdS and CdS:Ag(1%) thin films respectively and further enhanced upto 7 times on annealing the nanocomposite systems at 500 °C.