Multifunctional oxide nanostructures by metal-organic chemical vapor deposition (MOCVD)

The development of thin films, in the context of ongoing reduction in the size of electronic systems, poses challenging questions for the materials sciences of multifunctional nanostructures. These include the limits of size reduction, integration of heterogeneous functions, and system characterization or process control at an atomic scale. We present here different studies devoted to perovskite oxide materials (or materials with derived structure), where in specific directions of the crystal structure the atomic organization decreases down to a few nanometers, thus building nanostructures. In these materials, very original physical phenomena are observed in multilayers or superlattices, nanowires (NWs) or nanodots, mainly because strain, surfaces, and interfaces play here a predominant role and can tune the physical properties. Metal-organic chemical vapor deposition (MOCVD) routes have been used for the synthesis of oxide materials. We first introduce the basic rules governing the choice of metal-organic precursors for the MOCVD reaction. Next we discuss the principles of the pulsed injection MOCVD system. A laser-assisted MOCVD system, designed to the direct growth of 2D and 3D photonic structures, will also be described. Selected case studies will finally be presented, illustrating the powerful development of different oxide nanostructures based on dielectric, ferroelectric, or superconducting oxides, manganites, and nickelates, as well as first results related to the growth of ZnO NWs.