Influence of deposition pressure and rf power on the structure and electrical properties of Zr_0.8Sn_0.2TiO₄ thin films prepared by rf magnetron sputtering

ZnO-doped Zr_0.8Sn_0.2TiO₄ (ZST) films deposited on n-type Si (100) substrates at different deposition pressures and if powers were investigated. The structural and morphological characteristics analyzed by x-ray diffraction (XRD), atomic force microscopy, and scanning electron microscopy were found to be affected by deposition conditions, such as deposition pressure (2, 5, and 8 mTorr) and rf power (250, 350, and 450 W). Highly oriented ZST (101) and (111) perpendicular to the substrate surface were identified at a deposition pressure of 8 mTorr and rf power of 450 W. The XRD showed that the deposited films exhibited a polycrystalline microstructure. The grain size of the film increased with increasing rf power. From observing the surface morphology, ZST thin films exhibit a columnar structure. The electrical properties were measured using capacitance-voltage and current-voltage measurements on metal-insulator-semiconductor capacitor structures. The leakage current decreased with increasing rf power and deposition pressure. As rf power=450 W and deposition pressure=8 mTorr, a leakage-current density of 2.26 × 10^-9 A/cm² was obtained at 5 V.