Atomic layer-by-layer growth of oxide thin films by laser MBE

We have studied an atomic layer-by-layer thin film growth technique for complex oxide thin films and heterostructures. By using a laser-MBE system and monitoring the reflection high-energy electron diffraction (RHEED) intensity to control the flux for each atomic layer in-situ, we actively control the structure and stoichiometry down to the atomic layer level. In the growth of SrTiO$_{3}$ from the separate SrO and TiO$_{2}$ targets, or from metal Sr and oxide TiO$_{2}$ target, we studied the phases of the specular and diffraction spot intensities as well as that of the Kikuchi lines. UV Raman spectroscopy was used to probe the symmetry breaking due to the cation off-stoichiometry. Similar stoichiometry control as shown by reactive MBE has been demonstrated. We also studied the target preparation of various oxides, including the highly reactive La$_{2}$O$_{3}$ and BaO. We have successfully applied this atomic layer-by-layer growth method to the deposition of LaAlO$_{3}$ and LaNiO$_{3}$ thin films and superlattices.