Topmost surface and growth mechanism of BaTiO3 thin film grown by laser molecular beam epitaxy

The BaTiO3 thin film was grown epitaxially on SrTiO3(001) substrate by lase r molecular beam epitaxy (laser-MBE). The film growth process was monitored by in situ reflection high-energy electron diffraction (RHEED), the regula r RHEED intensity oscillation from the 0th-Bragg reflection shows an unit c ell layer-by-layer growth mode. The crystalline structure and the surface m orphology of the laser-MBE BaTiO3 film were characterized by X-ray diffract ion (XRD) and by atomic force microscopy (AFM), respectively. The XRD and A FM results show that laser-MBE BaTiO3 film exhibit the tetragonal c-axis or iented structure and an atomically smooth surface with a root mean square s urface roughness of 0.16 nm. The topmost surface of the film was studied by angle-resolved X-ray photoelectron spectroscopy (ARXPS), indicating the la ser-MBE BaTiO3 film is predominantly terminated with TiO2 atomic plane. The topmost surface of laser-ablated BaTiO3 film was also analyzed. The film g rowth mechanism was investigated in atomic scale.