Incorporation of colloidal Si nanoparticles into chemical bath solutions to synthesize nc-Si/CdS nanocomposite thin films

Abstract

Colloidal silicon nanoparticles (nc-Si) with diameters below 10 nm, were synthesized by the laser ablation of solids in liquids technique by ablating a bulk Si target immersed in deionized water. The obtained suspension was diluted in deionized water at volume ratios of 1:16, 2:15 and 4:13 in order to have different concentrations of Si nanoparticles. Each colloidal suspension was used to prepare precursor solutions for chemical bath deposition of nc-Si/CdS nanocomposite thin films with different nc-Si contents. According to UV–Vis Results, nanocomposite films reached optical transmission values of 90–98% for wavelengths above 500 nm, while the pure CdS reached values near 65%. Furthermore, the band gap increases linearly with nc-Si volume ratio in the bath. Photoluminescence emissions shifted to lower energies as nc-Si volume ratio increased. A signal associated to nanocrystalline Si appeared at 600 nm for nanocomposite films. Structural characterization showed no significant changes for nc-Si containing samples. • The laser ablation in solids technique can be combined with chemical bath deposition to synthesize nanocomposite thin films. • Nanocomposite films are crystalline. • Visible light emission from silicon nanoparticles embedded in CdS can be obtained.