Structure, composition and optical properties of Cu2ZnSnS4 thin films deposited by Pulsed Laser Deposition method

Polycrystalline Cu2ZnSnS4 (CZTS) thin films have been directly deposited on heating Mo-coated glass substrates by Pulsed Laser Deposition (PLD) method. The results of energy dispersive X-ray spectroscopy (EDX) indicate that these CZTS thin films are Cu-rich and S-poor. The combination of X-ray diffraction (XRD) results and Raman spectroscopy reveals that these thin films exhibit strong preferential orientation of grains along [1 1 2] direction and small Cu2-xS phase easily exists in CZTS thin films. The lattice parameters and grain sizes have been examined based on XRD patterns and Atom Force Microscopy (AFM). The band gap (E-g) of CZTS thin films, which are determined by reflection spectroscopy varies from 1.53 to 1.98 eV, depending on substrate temperature (T-sub). The optical absorption coefficient of CZTS thin film (T-sub=450 degrees C) measured by spectroscopic ellipsometry (SE) is above 10(4) cm(-1). (C) 2011 Elsevier B.V. All rights reserved.