The structural and electrical properties of thermally grown TiO2 thin films

We studied the structural and electrical properties of TiO2 thin films grown by thermal oxidation of e-beam evaporated Ti layers on Si substrates. Time of flight secondary ion mass spectroscopy (TOF-SIMS) was used to analyse the interfacial and chemical composition of the TiO2 thin films. Metal oxide semiconductor (MOS) capacitors with Pt or Al as the top electrode were fabricated to analyse electrical properties of the TiO2 thin films. We show that the reactivity of the Al top contact affects electrical properties of the oxide layers. The current transport mechanism in the TiO2 thin films is shown to be Poole–Frenkel (P–F) emission at room temperature. At 84 K, Fowler– Nordheim (F–N) tunnelling and trap-assisted tunnelling are observed. By comparing the electrical characteristics of thermally grown TiO2 thin films with the properties of those grown by other techniques reported in the literature, we suggest that, irrespective of the deposition technique, annealing of as-deposited TiO2 in O2 is a similar process to thermal oxidation of Ti thin films

Surface Acoustic Waves in Thin Films Nanometrology

Thin films nanometrology is an emerging field in nanoscience as the synthesis, processing and applications of nanostructured thin films require an in-depth knowledge of their elastic constants. The elastic energy of a surface acoustic wave propagating in a solid medium, is concentrated at the interface between the solid and air (or a sufficiently rarified medium); consequently, high frequency surface acoustic waves with sub-micrometer wavelengths are an extraordinary tool for a qualitative and quantitative elastic characterization of thin films. In this article, a short review is presented to describe the main ultrasound techniques based on surface acoustic waves for thin films characterization and to highlight the probing limits of acoustic nanometrology

High Curie temperature Mn 5 Ge 3 thin films produced by non-diffusive reaction

Polycrystalline Mn 5 Ge 3 thin films were produced on SiO 2 using magnetron sputtering and reactive diffusion (RD) or non-diffusive reaction (NDR). In situ X-ray diffraction and atomic force microscopy were used to determine the layer structures, and magnetic force microscopy, superconducting quantum interference device and ferromagnetic resonance were used to determine their magnetic properties. RD-mediated layers exhibit similar magnetic properties as MBE-grown monocrystalline Mn 5 Ge 3 thin films, while NDR-mediated layers show magnetic properties similar to monocrystalline C-doped Mn 5 Ge 3 C x thin films with $0.1 \leq x \leq 0.2.$ NDR appears as a CMOS-compatible efficient method to produce good magnetic quality high-curie temperature Mn 5 Ge 3 thin films

Molecular recognition on acoustic wave devices

Microporous thin films composed either of zeolite crystals embedded in sol-gel derived glass or of a molecular coupling layer, zeolite crystals and a porous silica overlayer, were formed on the gold electrodes of Quartz Crystal Microbalances (QCM). The microporosity of the thin films was characterized by in situ nitrogen and vapor sorption isotherms. Both preparation methods result in thin films with substantial microporosity. Selective adsorption based on molecular size exclusion from the microporous films could be achieved

Giant perpendicular magnetic anisotropy energies in CoPt thin films: Impact of reduced dimensionality and imperfections

The impact of reduced dimensionality on the magnetic properties of the tetragonal L1$_{0}$ CoPt alloy is investigated from ab-initio considering several kinds of surface defects. By exploring the dependence of the magnetocrystalline anisotropy energy (MAE) on the thickness of CoPt thin films, we demonstrate the crucial role of the chemical nature of the surface. For instance, Pt-terminated thin films exhibit huge MAEs which can be 1000% larger than those of Co-terminated films. Besides the perfect thin films, we scrutinize the effect of defective surfaces such as stacking faults or anti-sites on the surface layers. Both types of defects reduce considerably the MAE with respect to the one obtained for Pt-terminated thin films. A detailed analysis of the electronic structure of the thin films is provided with a careful comparison to the CoPt bulk case. The behavior of the MAEs is then related to the location of the different virtual bound states utilising second order perturbation theory.Comment: 10 pages, 7 figures, accepted in Journal of Physics: Condensed Matte