Characterisation and properties of Cu2ZnSnS4 thin films synthesised by sputtering from an alloy target

Abstract

Cu2ZnSnS4 (CZTS) thin films were synthesised on glass substrates by sulphurising sputtered metallic precursors in H2S + N2 atmosphere at 500 °C. The influences of the radio frequency (RF) sputtering power on the structure, surface morphology, optical and electrical properties of the thin films were investigated. Scanning electron microscopy, X-ray diffraction, Raman and UV–vis NIR spectroscopy were used to characterise the films. All the CZTS thin films exhibited a dominant kesterite structure. With increasing sputtering power, secondary phases in the films reduced, and the surface became more compact. The optimum quality films with poor-Cu and rich-Zn were obtained when the sputtering power was 90 W, and the optical band gap, carrier concentration, resistivity and mobility were 1.47 eV, 2.07 × 1018 cm−3, 2.37 Ω cm and 1.38 cm2 s−1 v−1, respectively. The optical and electrical properties of the CZTS thin films in relation to the secondary phases were discussed.