Electrochemically deposited nanostructured Cd-doped SnS thin films: Structural and optical characterizations

This paper investigates the impact of Cd-doping on the structural and optical properties of electrochemically deposited SnS thin films. The synthesized samples underwent characterization through various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, Fourier transform infrared spectrometer (FTIR), and UV-vis spectroscopy. According to the XRD analysis, the undoped SnS material exhibited a crystallite size (D) of 20 nm. However, as the Cd-doping concentration increased, the D initially increased and then decreased. The substitutional incorporation of Cd into SnS lattice was confirmed by XRD results. The inclusion of Cd-dopant into SnS lattice was validated through EDX analysis. SEM images demonstrated that appropriate Cd-doping into the SnS lattice can enhance crystalline nucleation, growth, and morphology. The absorption spectra of Cd 2-4 samples were higher than that of Cd 1, primary due to their increased film thickness and altered morphology type. The Cd 2 and Cd 3 samples exhibited higher R % values than Cd 1, associated with their superior crystalline quality. The deposited SnS samples exhibited a very high absorption coefficient (alpha) ranging from 10 to 25 x 104 cm(-1), making them suitable as an absorber layer. The refractive index (n) value of the Cd 2 sample at wavelengths of 400-1000 nm surpassed all other samples due to its larger crystallite size. The Eg for undoped SnS was 1.57 eV, which initially decreased to 1.30 eV and then increased to 1.81 eV after Cd-doping. The Raman analysis confirmed the successful formation of the SnS phase in all samples. Based on the obtained results, it can be concluded that the Cd-dopant improves the structural and optical characterizations of SnS thin films.