Influence of radio frequency (RF) magnetron sputtering power on structural, surface morphology and optical properties of sputter-coated CaCu3Ti4O12 (CCTO) thin films
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Date
2017-07
Authors
Siti Nursalma Binti Ayub
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Abstract
Calcium copper titanate (CaCu3Ti4O12, CCTO) especially in the form of thin films has created major interests particularly in the fabrications of resonator, capacitor and sensor. It is noteworthy for its extremely large dielectric permittivity (εr) and low dielectric loss (tan δ). One of the methods to deposit CCTO thin films is by using radio frequency (RF) magnetron sputtering. The parameters often studied during the deposition of CCTO thin films are temperature and pressure. Nevertheless, there is lack of researches varying the other parameter which is the sputtering power. The objective of this dissertation is to investigate the influence of RF magnetron sputtering power on structural, surface morphology and optical properties of sputter-coated CCTO thin films. The influence of varying RF power for depositing CCTO thin films to its properties has been studied. During this work, CCTO thin films are deposited successfully on indium tin oxide (ITO) substrates by using RF magnetron sputtering with the power of 100 W, 200 W, 250 W and 300 W, respectively. The deposited CCTO thin films are tested with several characterization methods to evaluate its structural, surface morphology and optical properties. The structural and surface morphology of CCTO thin films are determined by X-ray diffraction (XRD), atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), respectively. The optical properties are observed using ultraviolet–visible (UV-Vis) spectrophotometer. XRD patterns showed four peaks centred at 2θ= 30.30°, 34.70°, 50.59°, 60.6° are matched to reflection planes of (112), (022), (033), and (224), respectively, belongs to ICDD data card no. 98-005-8088 of CCTO. The crystallite size was found to increase with increment of RF power. AFM and FESEM confirmed that with the increase of RF power, it increased the grain and pore size of CCTO thin films. The surface roughness of CCTO thin films also increase with RF power from 1.6 nm to 2.3 nm. Finally, for the optical properties, the optical energy band gap increased from 3.20 eV to 3.44 eV with the increase of RF power. Therefore, structural, surface morphology and optical properties of CCTO thin films are found to be influenced by the RF magnetron sputtering power.