Atypical Deposition Temperature of CZTS Thin Films in Spray-Pyrolysis Technique: Impact on Surface Morphology, Phase, and Chemical Composition

Abstract

In this work, thin films of Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ZnSnS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> were deposited by the custom-made laboratory spray-pyrolysis system at atypical high deposition temperatures in the range from 723 K to 798 K without further annealing and sulfurization. The impact of various deposition temperatures on the surface morphology, phase, and chemical composition was investigated in detail. It was determined that each film has a tetragonal crystal structure with a phase of kesterite type CZTS. The changes in the deposition temperature have a substantial effect on the crystalline structure. The calculations found that with increasing temperature, there is an effect of lattice shrinkage. However, the coherent scattering region's calculated values indicate that films deposited at a higher temperature have a lower concentration of dislocations. It was established that there is an axial growth of the texture, mainly in the direction (112). With increasing deposition temperature, the orientation factor increased, indicating an improvement in the quality of texture. The surface morphology of films has a grain-like structure. The average grain diameter is 10-20 μm. EDS analysis showed slight deviations of sulfur concentration from stoichiometry, but the values are within normal limits for CZTS.