Bath atomic composition and deposition time influence on the properties of nanostructured CdS_0.5Se_0.5 thin films synthesized by CBD

Chemical Bath Deposition (CBD) was used to grow CdS_1-xfSe_xf (x_f = 0.5) thin films on Corning glass substrates at 75 C. The atomic composition of the bath was varied until an x_f of 0.5 was obtained, maintaining the deposition time at 120 min. Then the deposition time was modified from 5 to 360 min. The structural and optical properties of the films were analyzed by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-Ray Diffraction, UV-Vis Spectroscopy, Profilometry and Inductive Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). A bath atomic composition of Cd:S:Se equal to 0.76:0.55:0.45 was employed to obtain a film of x_f = 0.5. The films are constituted by clusters of semispherical nanoparticles (φ_av = 15 nm), which are well-arranged in a "nanoworm" structure. The nucleation time of the particles is lower than 5 min. All the films are polycrystalline with hexagonal phase and preferentially orientated on the (002) plane. The crystal size (11-6 nm) and the band gap (2.17-1.99 eV) decrease with the content of Se and remain constant with the deposition time. The composition x_f = 0.5 is achieved at different times to the heterogeneous (60 min) and homogeneous reactions (15 min). The kinetics of deposition and the consumption rate of Se change in a similar way, reaching the stability after 60 min.