Optimization of DC-Magnetron Sputtered Molybdenum (Mo) thin Film Electrodes for Electrodeposited CZTS Solar Cells

Abstract

In present work, we have prepared molybdenum (Mo) thin films having low resistivity and good adhesion to corning substrates by using DCmagnetron sputtering. The influence of working gas pressure on electrical, structural, morphological, optical and topological properties of Mo thin films have been investigated using various techniques such as Hall Effect measurement, x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV-Visible spectroscopy, non-contact-atomic force microscopy (NC-AFM) etc. Hall Effect measurements showed that the electrical resistivity of Mo films increases with increase in working gas pressure. The enhancement in adhesion of Mo with increase in working gas pressure was observed by Cross-hatch cut and Scotch tape adhesion test. As-deposited Mo films showed preferred orientation in (110) direction and decrease in crystallite size with increase in working gas pressure. It also showed that the Mo films deposited at 0.01 mbar exhibit compressive strain while those deposited at 0.05 mbar and above exhibit tensile strain. FE-SEM analysis showed that all Mo films have dense, homogeneous and crack-free microstructures. NC-AFM characterization showed that surface roughness of films increases with increase in working gas pressure. The as-synthesized Mo thin films were then successfully used to deposit Cu ZnSnS (CZTS) 2 4 layer by electrochemical deposition. Kesterite-CZTS thin films with preferred orientation along (112) direction were synthesized at room temperature by single step method through electrodeposition-annealing route.