Structural and Optical Properties of Cu2NiSnS4 thin Films Synthesized Through Thermal Evaporation Technique

Abstract

This paper investigates the physical properties of the thermally evaporated earth-abundant Cu2NiSnS4 (CNTS) thin films grown on glass substrates that are either unheated or heated to 100 or 200°C. The as-grown films deposited on unheated substrates were then annealed in air at 100°C, 200, and 300°C. The samples' crystalline structure was examined using the X-ray diffraction technique. The obtained XRD patterns indicated amorphous structure for as grown and air annealed films. Whereas those deposited, respectively, on 100°C and 200°C heated substrates displayed the appearance of CNTS related peaks. The estimated crystallite size average was found to be roughly 19 nm. CNTS thin-film optical properties were analyzed using UV-VIS-NIR spectrophotometry. The optical measurements demonstrated that the films had significant visible range absorption coefficient (10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup>–10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup>cm-1). The CNTS sample's direct band-gap was determined to be between 1.77 and 1.57 eV. Electrically, using the hot probe method, the electrical p-type conductivity of CNTS thin coating was confirmed. These characteristics make CNTS thin films appropriate as an active layer for solar cell applications.