CZTS films from three different routes: crystallite size-dependent properties

Abstract

In this study, CZTS thin films with different crystallite sizes were fabricated by dip, spin and spray techniques followed by sulphurization in N2 + H2S atmosphere. XRD and Raman studies were employed to confirm phase purities of the films. Dip coated films possessed lower grain size while higher grain size was observed in the spray coated films. Structural, optical and electrical properties of the films were studied with respect to their crystallite size. Cu/(Zn + Sn) and Zn/Sn elemental ratios of the dip, spin and spray coated films estimated were in reasonable agreement with the corresponding values reported in high performance CZTS devices. Optical band gaps determined were in the range 1.39–1.48 eV and the optical absorption coefficients were of the order of 105 cm−1 in the visible region. Carrier concentration, mobility and resistivity were measured by Hall Effect measurements. The study revealed that crystallite size and coating technique influence structural, optical and electrical properties of CZTS thin films.