Opto-electronic properties of copper-zinc-sulfide thin films grown via metalorganic-chemical vapor deposition technique at different flow rates

Abstract

In this work, copper zinc sulfide (CZS) ternary thin films were prepared from the pyrolysis of a Bis-(morpholinodithiato-s,s’)-Cu-Zn precursor using metal-organic chemical vapor deposition technique maintained at 450 ℃ in ambient nitrogen as the carrier gas. The deposition flow rate was varied to study its effect on the optoelectronic properties of CZS films. The particle-induced X-ray emission technique (PIXE) of the prepared single solid source precursor shows the presence of copper, zinc, and sulfur. The Fourier transform infrared spectrophotometer of the precursor reveals the metal-metal bond attachment to the ligand at a very low wavenumber. The XRD spectra reveal the formation of the hexagonal closed-packed structure of CZS films with a preferred orientation along the [111] direction. The film crystallite size is found to increase from 10.4 to 12.2 nm as the flow rate increases, while the dislocation density and stress decrease as the deposition flow rate increases. The SEM analysis revealed an improvement in the growth rate of the grains as the flow rate increased. The transmittance of the deposited CZS films was found to increase from 58% to 84.2% in the infrared region with an increase in band gap from 3.08 – 3.64 eV as the flow rate increased. The deposited film shows ohmic properties and an increase in conductivity from 0.243 to 0.847 (Ω cm)-1, while the resistivity decreases as the flow rate increases. These observations provide room for the deposited CZS film to serve as a potential material for optoelectronics and window layer solar cell devices.