Substrate temperature effect during the deposition of (Cu/Sn/Cu/Zn) stacked precursor CZTS thin film deposited by electron-beam evaporation

Abstract

Kesterite-Cu2ZnSnS4 (CZTS) thin films were deposited on molybdenum (Mo) coated glass substrates using electron-beam evaporation from stacked layer precursor (Cu/Sn/Cu/Zn). Influence of substrate temperatures during the deposition on the morphological, optical and structural properties of CZTS thin films were investigated using FE-SEM, EDS, Raman, UV–Vis and XRD methods. X-ray diffraction studies revealed that CZTS films deposited at 310 °C possess kesterite structure with preferential growth along (112) plane. FE-SEM studies revealed that the surface of the CZTS film contains spherical shaped grains distributed on the surface, the surface becomes smooth and the grain size increases with increase of the substrate temperature. Size, shape, and distribution of the elements and their effect on the CZTS films surface were studied as a function of substrate temperature. With increase of substrate temperature, the band gap value of CZTS thin films reduce from 1.46 to 1.11 eV. At 310 °C, Hall coefficient study showed that the CZTS film has p-type conductivity with low resistivity of 4.23 Ω cm. Solar cells were fabricated on a soda lime glass (SLG) substrate with the following structure SLG/Mo/Cu2ZnSnS4/CdS/i-ZnO Al:ZnO/Al. The optimized solar cell has a conversion efficiency of 2.4% with Jsc = 12.5 mA/cm2, Voc = 332 mV and FF = 58.0.