Epitaxial growth of BiFeO 3 films on SrRuO 3 /SrTiO 3

We have investigated the influence of growth parameters on the surface morphology of BiFeO3 (BFO) thin films prepared by pulsed laser deposition on SrTiO3 (001) substrates with SrRuO3 buffer layers. High quality epitaxial BFO thin films are obtained by controlling the laser pulse energy (EL), substrate temperature (TS) and oxygen partial pressure (Po2). It is found that the surface morphology is sensitive to both TS and Po2, and the root-mean-square roughness decreases initially and increases subsequently with increasing TS or Po2. Epitaxial BFO thin films with atomically smooth surface are successfully prepared in step flow growth mode at EL = 100 mJ, TS = 700 °C and Po2 = 13 Pa. Using X-ray diffraction, high-resolution cross-sectional transmission electron microscopy and piezoelectric force microscopy, the crystallinity, epitaxy and ferroelectricity of the BFO thin films prepared in optimal growth conditions have been studied. A growth diagram is constructed to delineate the growth window of high quality epitaxial BFO films with step and terrace topography.