Characteristics of CdS thin films deposited on glass and Cu(In,Ga)Se2 layer using chemical bath deposition

The characteristics of CdS thin films deposited on glass and Cu(In,Ga)Se2 (CIGS) thin films using a chemical bath deposition method were investigated. The concentration ratio of [S] to [Cd] in the solution and the deposition temperature were varied as key parameters. As the [S]/[Cd] ratio increased, the deposition rates decreased and grains of CdS formed as clusters. When the deposition temperature increased, the deposition rate increased and the grain size decreased, resulting in a circular grain shape. The [S]/[Cd] ratio and deposition temperature were found to have a great effect on the film stoichiometry, surface morphology and transmittance of CdS films. XPS analysis revealed that CdS films contained a significant amount of O, and the interdiffusion between the CdS and CIGS films took place. As the [S]/[Cd] ratio and deposition temperature increased, the CdS films showed good stoichiometry, smooth surface morphology and high transmittance.