Thermal stability of amorphous LaScO3 films on silicon

The thermal stability of amorphous LaScO3 thin films deposited by molecular-beam deposition directly on (001) Si was investigated by high-resolution transmission electron microscopy (HRTEM), transmission infrared absorption spectroscopy (IRAS), and x-ray diffraction (XRD). IRAS indicated that the as-deposited films contained < 0.1 A of SiO2 at the interface between LaScO3 and silicon. XRD studies showed that the films remained amorphous after annealing in N-2 at 700 degrees C, although HRTEM showed structural order on an similar to 1 nm length scale even in the as-deposited films. By 800 degrees C, the LaScO3 had started to crystallize and formed a similar to 5 nm thick Sc-deficient interlayer between it and silicon. (c) 2006 American Institute of Physics

First-principles calculation of the band offset at BaO/BaTiO3_3 and SrO/SrTiO3_3 interfaces

We report first-principles density-functional pseudopotential calculations on the atomic structures, electronic properties, and band offsets of BaO/BaTiO$_3$ and SrO/SrTiO$_3$ nanosized heterojunctions grown on top of a silicon substrate. The density of states at the junction does not reveal any electronic induced interface states. A dominant perovskite character is found at the interface layer. The tunability of the band offset with the strain conditions imposed by the substrate is studied. Using previously reported theoretical data available for Si/SrO, Si/BaO and BaTiO$_{3}$/SrRuO$_{3}$ interfaces we extrapolate a value for the band alignments along the whole gate stacks of technological interest: Si/SrO/SrTiO$_3$ and Si/BaO/BaTiO$_3$/SrRuO$_3$ heterostructures.Comment: 12 pages, 6 figures, submitted to Phys. Rev.

Study of microstructure in SrTiO₃/Si by high-resolution transmission electron microscopy

©2002 Materials Research Society. The original publication is available at: http://www.mrs.org/DOI: 10.1557/JMR.2002.0030Microstructure in the SrTiO₃/Si system has been studied using high-resolution transmission electron microscopy and image simulations. SrTiO₃ grows heteroepitaxially on Si with the orientation relationship given by (001)STO//(001)Si and [100]STO//[110]Si. The lattice misfit between the SrTiO₃ thin films and the Si substrate is accommodated by the presence of interfacial dislocations at the Si substrate side. The interface most likely consists of Si bonded to O in SrTiO₃. The alternative presentation of Sr and Si atoms along the interface leads to the formation of 2× and 3× Sr configurations. Structural defects in the SrTiO₃ thin film mainly consist of tilted domains and dislocations

Epitaxial BiFeO3 thin films on Si

BiFeO3 was studied as an alternative environmentally clean ferro/piezoelectric material. 200-nm-thick BiFeO3 films were grown on Si substrates with SrTiO3 as a template layer and SrRuO3 as bottom electrode. X-ray and transmission electron microscopy studies confirmed the epitaxial growth of the films. The spontaneous polarization of the films was ~45μC/cm2. Retention measurement up to several days showed no decay of polarization. A piezoelectric coefficient (d33) of ~60 pm/V was observed, which is promising for applications in micro-electro-mechanical systems and actuators.Published versio