Effects of deposition time on properties of CaCu3Ti4O12 thin film deposited on ITO substrate by RF magnetron sputtering at ambient temperature

Abstract

CaCu3Ti4O12 (CCTO) thin film was deposited on ITO substrate using radio frequency (RF) magnetron sputtering at various deposition times (1–4 h). The significant effects of deposition time on the structural, morphological, optical and electrical properties were systematically investigated using XRD, AFM, FESEM, UV–Vis, and Hall Effect measurements. XRD study showed that all sputtered films have cubic structure. Higher deposition times of up to 4 h enhanced the film's crystallinity, as demonstrated by the increase in peak intensity and incremental change in crystal size (from 19.5 to 23.6 nm). Roughness (Ra) and root mean square (RMS) values were found to increase from 1.99 to 5.15 nm and 2.66–6.68 nm, respectively, when deposition times were increased. The surface morphology of CCTO thin films were found to be smooth, compact, and densely island-shaped in structure. The film thickness increased from 270 to 330 nm with increase in deposition time. Increase in deposition time also affected the optical transmittance values which declined to 70% at the visible range and the optical energy band gap which decreased from 3.76 to 3.29 eV. At 4 h deposition time, the films showed lower resistivity (of 8.22 Ω/sq), and higher Hall mobility (78.43 cm2/Vs) and carrier concentration (9.84 × 1015 cm−2). The conclusion drawn from this study revealed that by controlling the deposition time, better properties of CCTO thin films can be achieved.