X-RAY DIFFRACTION, ATOMIC FORCE MICROSCOPY AND RAMAN SPECTROSCOPY STUDIES OF MICROSTRUCTURE OF BiFeO <sub>3</sub> THIN FILMS ON Pt/Ti/SiO <sub>2</sub>/Si (111) SUBSTRATES
A set of BiFeO <sub>3</sub> (BFO) thin films with different thicknesses deposited on Pt/Ti/SiO <sub>2</sub>/Si (111) substrates and LaNiO <sub>3 </sub>(LNO)-buffered Pt/Ti/SiO <sub>2</sub>/Si (111) substrates using a radio-frequency magnetron sputtering technique were studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and Raman spectroscopy. The XRD patterns demostrated, that all BFO thin films were polycrystalline with a distorted rhombohedral structure, even though there were distinct changes in the main peak positions and intensities. The AFM topography images also clearly illustrated different surface profiles of these thin films. A grain size of the thin films deposited on the LNO-buffered subtrates was greatly decreased, comparing to that of the thin films deposited directly on the Pt/Ti/SiO <sub>2</sub>/Si (111) substrates. Raman-active modes, which can be classified as 4A <sub>1</sub> and 9E modes, have been observed in the Raman spectra of the BFO thin films. Variations in the Raman shift and bandwidth of different BFO thin films reveal an influence of the thin film and buffer layer thicknesses on the film microsturcture.