Optical and electrical investigations on Cu2SnS3 layers prepared by two-stage process

Cu₂SnS₃ thin films were prepared using a simple and phase-controlled two-stage process. Initially, Cu-Sn precursors were deposited by DC sputtering, followed by sulfurization at different temperatures (T_s) that vary in the range, 150 - 500 °C. An exhaustive study of the optical properties in relation to sulfurization temperature was performed using transmission and reflectance measurements. The estimated optical absorption coefficient for all the layers was very high and found to be > 10⁴ cm^?1. The optical band gap was determined using Tauc plots and it varied in the range, 1.49–2.34 eV with an increase of T_s. The refractive index (n) and the extinction coefficient (k) were also obtained. The optical properties like dispersion parameters, dielectric constant, dissipation factor, optical conductivity, surface energy loss function, volume energy loss function and optical haze were also calculated. Further, analysis of electrical properties such as electrical resistivity, mobility and carrier density of the prepared films with sulfurization temperature was made in order to verify the suitability of synthesized CTS layers for solar cell application.