Effect of Ar:N2 flow rate on morphology, optical and electrical properties of CCTO thin films deposited by RF magnetron sputtering

Calcium copper titanate (CCTO) thin films were deposited on indium tin oxide (ITO) substrates using radio frequency (RF) magnetron sputtering, at selected Ar:(N)2 flow rates (1:1, 1:2, 1:4, and 1:6 sccm) at ambient temperature. The effect of Ar:N-2 flow rate on the morphology, optical and electrical properties of the CCTO thin films were investigated using FESEM, XRD, AFM, Hall effect measurement, and UV-Vis spectroscopy. It was confirmed by XRD analysis that the thin films were produced is CCTO with cubic crystal structure. As the flow rate of Ar:N-2 increased up to 1:6 sccm, the thin film thickness reduced from 87 nm to 35 nm while the crystallite size of CCTO thin film decreased from 27 nm to 20 nm. Consequently, the surface roughness of thin film was halved from 8.74 nm to 4.02 nm. In addition, the CCTO thin films deposited at the highest Ar:N-2 flow rate studied, at 1:6 sccm; are having the highest sheet resistivity (13.27 Omega/sq) and the largest optical energy bandgap (3.68 eV). The results articulate that Ar:N-2 flow rate was one of the important process parameters in RF magnetron sputtering that could affect the morphology, electrical properties and optical properties of CCTO thin films.