Effect of selenization time on optical, electrical properties and structure of CZTSSe thin films

Abstract

In this paper, we present a fabrication process of high crystallinity CZTSSe absorber layer. The CZTS structure is firstly prepared by spin-coating method, and then the film is converted into CZTSSe via selenization process using graphite box and tube furnace. The Se powder has been loaded into graphite box and used as source of selenizing vapors. Keeping the annealing temperature as constant, the structural, optical, electrical properties, and composition of CZTSSe thin films are investigated by changing the annealing time. X-ray diffraction revealed that these thin films are high crystallinity and strong preferential orientation along the (112) direction. The Raman spectra show the presence of the kesterite CZT Se phase which confirm the linkage of Se in structure. The band gaps (E_g) of the CZT Se thin films varied from 1,19 to 1.62 eV depend on the selenization times. At optimal annealing times, the p-type CZTSSe film has bandgap energy, hole concentration, and resistivity of 1,19 eV, 2,68 x 10¹⁹ cm^-3 and 0,86Ω.cm respectively which are suitable for photovoltaic application.