Investigations on post sulphurised Cu2ZnSnS4 absorber layer thin films prepared using radio frequency magnetron sputtering

Abstract

Copper zinc tin sulfide (CZTS) quaternary semiconductor thin films were prepared using binary sulfur rich sputtering targets - copper sulfide (CuS), zinc sulfide (ZnS), and tin sulfide (SnS) by Radio Frequency Magnetron Sputtering with the stacking sequence CuS/ ZnS/ SnS at a substrate temperature of 300 °C. The films were then subsequently sulphurised at 350 °C in Hydrogen Sulfide atmosphere for 60 min. X-ray diffraction studies carried out on the CZTS films revealed the presence of CZTS kesterite phase along the 〈112〉 and 〈220〉 directions. X- ray diffraction results were validated by Raman spectroscopy. The composition of CZTS thin films were confirmed using X-Ray photoelectron spectroscopy and the atomic percentage of the individual elements were quantitatively estimated. The Valance band spectra and Ultra-violet photoelectron spectroscopy were used to study the electronic properties of the sulphurised CZTS thin films. The optical properties of CZTS thin films were studied using Ultraviolet - visible spectrophotometer and the optical band gap was found to be 1.477 eV. The Hall Effect measurements confirmed the p-type nature of the films and the results are discussed.