A foundation for complex oxide electronics -low temperature perovskite epitaxy.

As traditional silicon technology is moving fast towards its fundamental limits, all-oxide electronics is emerging as a challenger offering principally different electronic behavior and switching mechanisms. This technology can be utilized to fabricate devices with enhanced and exotic functionality. One of the challenges for integration of complex oxides in electronics is the availability of appreciable low-temperature synthesis routes. Herein we provide a fundamental extension of the materials toolbox for oxide electronics by reporting a facile route for deposition of highly electrically conductive thin films of LaNiO3 by atomic layer deposition at low temperatures. The films grow epitaxial on SrTiO3 and LaAlO3 as deposited at 225 °C, with no annealing required to obtain the attractive electronic properties. The films exhibit resistivity below 100 µΩ cm with carrier densities as high as 3.6 · 1022 cm-3. This marks an important step in the realization of all-oxide electronics for emerging technological devices.

Surface Forces Apparatus Measurements of Interactions between Rough and Reactive Calcite Surfaces.

nm-Range forces acting between calcite surfaces in water affect macroscopic properties of carbonate rocks and calcite-based granular materials and are significantly influenced by calcite surface recrystallization. We suggest that the repulsive mechanical effects related to nm-scale surface recrystallization of calcite in water could be partially responsible for the observed decrease of cohesion in calcitic rocks saturated with water. Using the surface forces apparatus, we simultaneously followed the calcite reactivity and measured the forces in water in two surface configurations: between two rough calcite surfaces (CC) and between rough calcite and a smooth mica surface (CM). We used nm-scale rough, polycrystalline calcite films prepared by atomic layer deposition. We measured only repulsive forces in CC in CaCO3-saturated water, which was related to roughness and possibly to repulsive hydration effects. Adhesive or repulsive forces were measured in CM in CaCO3-saturated water depending on calcite roughness, and the adhesion was likely enhanced by electrostatic effects. The pull-off adhesive force in CM became stronger with time, and this increase was correlated with a decrease of roughness at contacts, the parameter which could be estimated from the measured force-distance curves. That suggested a progressive increase of real contact areas between the surfaces, caused by gradual pressure-driven deformation of calcite surface asperities during repeated loading-unloading cycles. Reactivity of calcite was affected by mass transport across nm- to µm-thick gaps between the surfaces. Major roughening was observed only for the smoothest calcite films, where gaps between two opposing surfaces were nm-thick over µm-sized areas and led to force of crystallization that could overcome confining pressures of the order of MPa. Any substantial roughening of calcite caused a significant increase of the repulsive mechanical force contribution.

Rubidium containing thin films by atomic layer deposition.

The application range for atomic layer deposition (ALD) has now been extended to include the deposition of rubidium-containing films, enabling the deposition of new and exploratory types of compounds by ALD. The properties of rubidium t-butoxide as an ALD precursor are promising, revealing similar behavior as its lithium, sodium and potassium counterparts. The deposition of rubidium containing films is reported as proof of concept through the Rb-Ti-O and Rb-Nb-O systems. Rubidium content in the doping level range of Rb is controllably achieved in Rb:TiOx up to 20%, whereas Rb can be introduced as a major component in Rb:NbOx. Perovskite RbNbO3, otherwise unattainable in bulk systems under ambient conditions, is shown to be stabilized on SrTiO3 (100) substrates. This report opens up the investigation of thin films of new and unexplored systems, not only in the world of ALD, but in materials chemistry in general.

Comparison of different coating techniques on the properties of FucoPol films.

Plasma deposition, liquid flame spray (LFS) and atomic layer deposition (ALD) were used to form inorganic coatings in new exopolysaccharide (FucoPol) biodegradable films. Coated films were characterised in terms of surface, optical and barrier properties in order to evaluate their potential use in food packaging. FucoPol films presented dense and homogeneous surface with instant water contact angle of 95̊. Plasma deposition of perfluorohexane (PFH) on FucoPol surface has not shown significant improvement in the hydrophobic behaviour over the time. The FucoPol coating of SiO2 nanoparticles deposited by LFS and plasma deposition of PFH have shown higher instant water contact angle (135°) caused by coating surface roughness, but this hydrophobic behaviour was not stable over time. FucoPol films coated only with TiO2 deposited by ALD and combination of that with plasma deposition of PFH have shown stable water contact angle during time (90̊ and 115̊, respectively), transparency in the same order of magnitude and significantly lower permeability to water vapour (3.45×10-11mol/m s Pa and 3.45×10-11mol/m s Pa when compared to uncoated films with 5.32×10-11mol/m s Pa). Moreover, films coated with TiO2-PFH have also shown a permeability to oxygen of 1.70×10-16molm/m2sPa which is 67% lower than uncoated films.