Study on the introduction of Se into CdS thin films: Influence on the kinetics of the deposition and the structural and optical properties

CdS and CdS0.75Se0.25 thin films were prepared at different deposition times (5-180 min) and at 75 °C by chemical solution deposition. All the films are polycrystalline in nature; in the case of CdS, a mixture of cubic and hexagonal phase is present whereas the CdS0.75Se0.25 films show hexagonal phase. The CdS films are dense and homogeneous with good crystalline quality and band gap (Eg) values close to that of bulk material (2.48-2.52 eV). The properties of CdS0.75Se0.25 films are mainly affected by the deposition time. The growth is slow and disordered, the crystalline quality is low, and the increase of the strain is perceivable. The Eg changes from 2.41 to 2.25 eV. Room photoluminescence has been observed in both materials. The kinetics of the growth and the consumption rate of Cd, have a similar behavior for both systems presenting a two-regime process, however, the growth rate decreases when the Se is incorporated to the chemical solution.