Investigation of fractal feature of multiferroic BiFeO₃ thin films deposited on different substrates

Abstract

Fractal analysis is applied to study the surface properties of Multiferroic BiFeO3 (BFO) thin films deposited on three different substrates [Silicon (Si), SrTiO3 (111), and sapphire (Al2O3)] using pulsed laser deposition (PLD) technique. The structure of all the thin films deposited on different substrate are characterised by x-ray diffraction reveals rhombohedral symmetry with space group R3c. The dielectric permittivity and dielectric loss of BFO/SRO/STO(111) thin films were investigated as function of frequency at different temperature(300 K to 550 K). The surface morphology and micro structural properties were investigated by atomic force microscope (AFM). Higuchi's algorithm was applied on AFM micrographs for the estimation of fractal dimension of different samples. The Fractal dimension value of each 512 horizontal and vertical sections was obtained. The Hurst exponents for these samples were computed from the fractal dimension. The value of the Hurst exponent (H) for each substrate is found to be less than 0.5 which indicates anti-persistence behaviour of the surface. The film deposited on SrTiO3 (111) shows the smaller fractal dimension and higher Hurst exponent value as compared to the films deposited on Si and Al2O3, respectively.