Monitoring the growth of SrTiO 3 and La 0.66 Sr 0.33 MnO 3 thin films using a low-pressure Reflection High Energy Electron Diffraction system
Résumé
Oxides display a variety of electronic phenomena, including ferroelectricity, magnetism or multiferroicity. Recently, a large interest has raised from the interfaces between two oxides of few unit cells, which show unexpected electronic properties such as superconductivity or magnetism. Thus, the structural quality of interfaces as well as a precise control of the thickness are main challenges for researchers who grow oxide films. To achieve such a high quality interface and a careful control of the growth, Reflection High Energy Electron Diffraction in-situ monitoring, is often used and mounted in a pulsed laser ablation system. While high pressure is widely utilized, low pressure is rarely utilized for oxides except when coupled to a molecular beam epitaxy (MBE) chamber. Here, the preparation of high-quality oxide thin films is reported and the different factors which affect the reliability of such an approach are presented, i.e. the correlation between the observed intensity oscillations and the deposited thickness. It is shown that oxides thin films grown on SrTiO3 single crystals, in a low-pressure environment with the laser-MBE system, possess extremely high physical characteristics (magnetoresistance, ferroelectricity, ferromagnetism, metal/insulating transition) very close to the bulk values and that the interface is nearly perfect, of the same quality as found for semiconductors.