Improved chemical deposition of cobalt-doped CdS nanostructured thin films via nucleation-doping strategy: Surface and optical properties

Abstract

In the majority of the chemical deposition techniques used for doping thin films, dopant cations are usually added to the reaction simultaneously with the host cations, or even after the formation of the host matrix. This approach reduces the dopant efficiency and reproducibility of dopant-related properties. In the present work, the nucleation-doping strategy usually used for colloidal nanocrystals is extended into the chemical bath deposition technique to prepare cobalt-doped CdS nanostructured thin films. The Co:CdS thin films showed %2.5 doping yield with a root-mean-square roughness below 22 nm and absorption edge below 510 nm. The PL emission spectra of the films revealed two distinct peaks at 490 and 530 nm, attributed to the recombination processes through excitonic states and impurity levels, respectively. Almost all the experimental variables were optimized to reach a partially single-emission peak at 530 nm, which can prove the successful incorporation of Co ions into CdS nanostructures.