Doping of CdS nanoparticles

The doping of semiconductor nanoparticles is introduced and examined via doping of cadmium sulfide nanoparticles both by chemical bath deposition route with In3+ cations and by thermal annealing route with Cl− anions. The CdS nanoparticles (10–20 nm in size) were prepared by mixing CdCl2 and Na2S solutions stabilized with pyridine both in absence and in presence of InCl3 additives. The doping of the nanostructured CdS films prepared from CdS nanoparticles dispersions was performed by additives of aqueous CdCl2 solution followed by the film annealing. Due to the used doping procedure the increase of the film conductivity began at temperature ∼300 °C, which was far lower than temperature inducing the doping of polycrystalline CdS films and not yet enough for the noticeable recrystallization of CdS nanoparticles into larger domains. The In2S3 and CdCl2 doping of CdS nanoparticles resulted in changes in electronic absorption and luminescence spectra of the nanoparticle dispersions and films. The phenomenon of the easier doping of CdS nanoparticles is discussed in terms of the high surface energy of CdS nanoparticles.