Temperature and deposition time effect on properties and kinetics of cdse and CdS_0.25Se_0.75 films deposited by CBD

CdSe and CdS_0.25Se_0.75 thin films were grown by the Chemical Bath Deposition technique at different temperatures (50-90°C) and deposition times (5-180 min). Both kinds of films are polycrystalline, constituted by nanostructured clusters of particles. CdSe films consist in a mixture of cubic and hexagonal phases (4-8 nm crystal size), whereas only the hexagonal phase is observed in the CdS_0.25Se_0.75 ones (6±1 nm crystal size). A decrease on the CdSe films density was observed due to the sulfur introduction into the crystal lattice. The composition of the ternary films is affected by both temperature and deposition time. The Band gap values (E_g) are affected by temperature, atomic composition and deposition time, decreasing from 2.09 to 1.93 eV, showing a quantum confinement effect mainly in the CdSe films. The films thickness, ranging from 30 to 600 nm, increases as a function of temperature and deposition time. Photoluminiscence signal is improved after thermal treatment, evidenced by the radiative broad bands observed at 1.84 and 2.20 eV.