Characterization of Strontium Oxide Layers on Silicon for CMOS High-K Gate Stack Scaling

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7-August 11, 201

The chemistry of La on the Si(001) surface

This paper reports state-of-the-art electronic structure calculations of La adsorption on the Si(001) surface. We predict La chains in the low coverage limit, which condense in a stable phase at a coverage of 1/5 monolayer. At 1/3 monolayer we predict a chemically rather inert, stable phase. La changes its oxidation state from La(3+) at lower coverages to La(2+) at coverages beyond 1/3 monolayer. In the latter oxidation state, one electron resides in a state with a considerable contribution from La-d and f states.Comment: 10 pages, 13 figures, 3 table

Growth of Single Unit-Cell Superconducting La2−x_{2-x}Srx_xCuO4_{4} Films

We have developed an approach to grow high quality ultrathin films of La$_{2-x}$Sr$_x$CuO$_{4}$ with molecular beam epitaxy, by adding a homoepitaxial buffer layer in order to minimize the degradation of the film structure at the interface. The advantage of this method is to enable a further reduction of the minimal thickness of a superconducting La$_{1.9}$Sr$_{0.1}$CuO$_{4}$ film. The main result of our work is that a single unit cell (only two copper oxide planes) grown on a SrLaAlO$_4$ substrate exhibits a superconducting transition at 12.5 K (zero resistance) and an in-plane magnetic penetration depth $\lambda_{ab}(0)$ = 535 nm.Comment: to be published in "Solid State Electonics" special issue, conference proceedings of the 9th Workshop on Oxide Electronics, St-Pete Beach, FL, 20-23 november 2002 : 12 pages 4 figures in preprint versio

Domain-size-dependent exchange bias in Co∕LaFeO3

X-ray microscopy using magnetic linear dichroism of a zero-field-grown, multi-domain Co/LaFeO{sub 3} ferromagnet/antiferromagnet sample shows a local exchange bias of random direction and magnitude. A statistical analysis of the local bias of individual, micron-size magnetic domains demonstrates an increasing bias field with decreasing domain size as expected for a random distribution of pinned, uncompensated spins, which are believed to mediate the interface coupling. A linear dependence with the inverse domain diameter is found

Studies of the magnetic structure at the ferromagnet–antiferromagnet interface

Antiferromagnetic layers are a scientifically challenging component in magneto-electronic devices such as magnetic sensors in hard disk heads, or magnetic RAM elements. In this paper we show that photo-electron emission microscopy (PEEM) is capable of determining the magnetic structure at the interface of ferromagnets and antiferromagnets with high spatial resolution (down to 20 nm). Dichroism effects at the L edges of the magnetic 3d transition metals, using circularly or linearly polarized soft x-rays from a synchrotron source, give rise to a magnetic image contrast. Images, acquired with the PEEM2 experiment at the Advanced Light Source, show magnetic contrast for antiferromagnetic LaFeO{sub 3}, microscopically resolving the magnetic domain structure in an antiferromagnetically ordered thin film for the first time. Magnetic coupling between LaFeO{sub 3} and an adjacent Co layer results in a complete correlation of their magnetic domain structures. From field dependent measurements a unidirectional anisotropy resulting in a local exchange bias of up to 30 Oe in single domains could be deduced. The elemental specificity and the quantitative magnetic sensitivity render PEEM a perfect tool to study magnetic coupling effects in multi-layered thin film samples

Wafer level integration of epitaxial piezoelectric thin films for novel NEMS, MEMS and MOEMS applications

Pb(Zr, Ti)O3 (PZT) and (PhMg1/3Nb2/3O3)2/3-CPbTiO3)1/3 (PMN-PT) thin films are epitaxially deposited on 200 mm wafers using Solmates' Pulsed Laser Deposition (PLD) platform. Epitaxy is achieved using an optimized TiN template layer on the lattice mismatched silicon. SrTiO3 was used as buffer layer and LaNiO3 as oxide bottom electrode after which PZT and PMN-PT were deposited. A fully epitaxial thin film stack was confirmed by XRD analysis and the degree of epitaxy was found to be homogeneous across the wafer. The ferro- and piezoelectric properties were measured and found to be stable upon 103 switching cycles.publishedVersio

Growth and characterization of ferroelectric LaTiO₃.₅ thin films

Depending upon the oxygen content x, LaTiO3+x can be a semiconductor, a metal, or a ferroelectric at room temperature. Using a thin-film approach, it is in principle possible to adjust the oxygen content in the growth direction and thus tune the electronic properties within the same sample. We report here on a systematic study of the epitaxial growth of LaTiO3.5 films on SrTiO3 (110) substrates using molecular beam epitaxy. The epitaxial behaviour and the growth mechanism of these films have been investigated by means of X-ray diffraction, transmission electron microscopy, and in situ reflection high-energy electron diffraction analysis.status: publishe