Swift heavy ion induced structural phase generation and enhanced luminescence from CdS based nanocomposites

Synthesis and modification of CdS:SiO2 and Cd0.99Ag0.01S:SiO2 nanocomposite thin films grown at substrate temperature 200 °C by pulsed laser deposition (PLD) followed by swift heavy ion irradiation (SHII) using 120 MeV Ag9 + ions is reported. The structural evolution of CdS phase in SiO2 after SHII is illustrated by glancing angle x-ray diffraction patterns and micro-Raman spectra. Transmission electron microscopy (TEM) images clearly show the growth of CdS/Cd0.99Ag0.01S nanoparticles in SiO2 matrix under the influence of SHII. Photoluminescence (PL) spectra show two emission peak at ~ 2.34 eV and ~ 3.05 eV assigned for green emission (GE) and violet emission (VE) respectively. The VE assumed to be originated due to the band edge emission and GE identified as the trap levels located between conduction band and valence band. The presence of emission from pristine films indicates that the crystalline domains are very small in films rather than the particles are amorphous in nature. A systematic increment in PL emission intensity corresponding to trap emission as a function of ion irradiation fluence is observed from the two nanocomposite systems. However, the behavior of band edge emission induced by SHII is quite different in two nanocomposite systems. SHII induced phase formation and emission intensity variation as a function of ion fluence are explained on the basis of thermal spike model.