Structural and optical characterization of Cu2SnSe3 thin films prepared by SILAR method

Phase pure Cu2SnSe3 thin films were successfully obtained on glass substrates by annealing of successive ionic layer adsorption and reaction (SILAR) deposited thin films at 623 K for an hour in selenium atmosphere. Structural, morphological, compositional, and optical properties of films were investigated, before and after annealing, via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Raman spectroscopy, and optical absorption measurements. XRD results showed that films were polycrystalline nature with cubic structure, the crystallinity was improved with annealing and the secondary phase of SnSe disappeared as well. SEM images revealed existence of the relatively big islands, which were formed overlapping large number of small grains, was observed on the surfaces. The images also showed a considerable change in the shape of the grains with annealing. EDAX measurements revealed that chemical composition of the annealed film was very close to the ideal value 2:1:3. The results of Raman measurement confirmed the formation of Cu2SnSe3 and disappearance of the secondary phase of SnSe after annealing. The optical absorption studies showed that the films have direct transitions with band gap energies of 1.38 eV and 1.34 eV before and after annealing, respectively. © 2016