Abstract
Cu2ZnSnS4 (CZTS) thin films have been prepared using a Spray pyrolysis technique. The evolution of CZTS, followed by an increase in thiourea concentrations [S] from 0.04 to 0.07 M, is investigated. EDX analysis exhibits a drastic increase of sulfur amount as the thiourea concentration increases. X-ray diffraction and Raman spectroscopy analysis confirmed the formation of CZTS kesterite structure with some spurious phases mainly at higher thiourea concentrations. Indeed, with further increase in [S], XRD reveals the appearance of a sharp and intense peak, which is assigned to Cu4Sn7S16. Optical analysis by means of transmission T(lambda) and reflection R(lambda) measurements allow to determine the optical absorption coefficient alpha for all CZTS compounds, it is larger than 10(4) cm(-1). The direct band gap energy value E-g can be deduced; it ranges from 1.59 to 1.74 eV. The broadening of E-g might be attributed to the ZnS secondary phase. (C) 2014 Elsevier Ltd. All rights reserved.