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The phenomenon of dopants migrating towards the surface against the concentration gradient may be useful to control junction depth for ultra-shallow profiles. We apply high-resolution SIMS—in combination with channelling Rutherford backscattering spectroscopy (RBS)—to reveal these subtle, yet highly significant changes in dopant profiles during or after solid phase epitaxial regrowth (SPER) in germanium-preamorphized silicon. We observe redistribution for shallow implantations of arsenic in preamorphized Si towards the surface during SPER. This is caused by segregation of As in front of the amorphous/crystalline (a/c) Si interface. Also for boron anomalous behavior has recently been reported, showing preferential migration towards the surface after crystalline regrowth at high concentrations for shallow implantation of BF2+ in crystalline Si or B+ in Ge-preamorphized Si. Here, we investigate the time- and temperature-dependence of this phenomenon to clear up the mechanism for redistribution during crystalline regrowth. Redistribution of B is shown to occur only partly during SPER, most likely caused by segregation. Still, significant changes take place after completion of SPER during prolonged annealing. We propose that this is provoked by the locally steep concentration gradient of interstitials close to the surface after restoration of the crystalline structure. [Copyright &y& Elsevier]

Alcohol electrolysis using polymeric membrane electrolytes is a promising route for storing excess renewable energy in hydrogen, alternative to the thermodynamically limited water electrolysis. By properly choosing the ionic agent (i.e. H+ or OH−) and the catalyst support, and by tuning the catalyst structure, we developed membrane-electrode-assemblies which are suitable for cost-effective and efficient alcohol electrolysis. Novel porous electrodes were prepared by Atomic Layer Deposition (ALD) of Pt on a TiO 2 -Ti web of microfibers and were interfaced to polymeric membranes with either H+ or OH− conductivity. Our results suggest that alcohol electrolysis is more efficient using OH− conducting membranes under appropriate operation conditions (high pH in anolyte solution). ALD enables better catalyst utilization while it appears that the TiO 2 -Ti substrate is an ideal alternative to the conventional carbon-based diffusion layers, due to its open structure. Overall, by using our developmental anodes instead of commercial porous electrodes, the performance of the alcohol electrolyser (normalized per mass of Pt) can be increased up to ∼30 times. Image 1 • Alcohol electrolysis was carried out using acidic and alkaline polymeric membranes. • Using OH− conducting membranes is beneficial under appropriate operation conditions. • Atomic layer deposition (ALD) of Pt on a TiO 2 -Ti web of microfibers was carried out. • ALD results in more efficient catalyst utilization compared to commercial electrodes. • The TiO 2 -Ti substrate has an active role in electrocatalysis. [ABSTRACT FROM AUTHOR]

A novel catalyst design for electrochemical promotion of catalysis (EPOC) is proposed which overcomes the main bottlenecks that limit EPOC commercialization, i.e., the low dispersion and small surface area of metal catalysts. We have increased the surface area by using a porous composite electrode backbone made of (La 0.8 Sr 0.2 ) 0.95 MnO 3-δ /Ce 0.9 Gd 0.1 O 1.95 (LSM/GDC). Highly dispersed Pt nanoparticles with an average diameter of 6.5 nm have been deposited on LSM/GDC by atomic layer deposition (ALD). This novel design offers, for the first time, a controllable and reproducible method for the fabrication of EPOC catalysts. The bare electrode backbone shows negligible activity for propane oxidation, while in the presence of Pt nanoparticles a high catalytic activity is obtained above 200 °C. The performance of the Pt-loaded LSM/GDC catalyst was significantly improved by application of small currents ( I < 500 μΑ), leading to a 27–33% increase as a function of the open circuit catalytic rate, with apparent Faradaic efficiency values ranging from 1000 to 3860% at 300 °C. Our results demonstrate that EPOC is a valid approach for enhancing the catalytic activity of nano-structured catalysts. [ABSTRACT FROM AUTHOR]

We report on the gas phase synthesis of highly crystalline and homogeneously alloyed Si 1−x Ge x nanocrystals in continuous and pulsed plasmas. Agglomerated nanocrystals have been produced with remarkable control over their composition by altering the precursor GeH 4 gas flow in a continuous plasma. We specially highlight that in the pulsed plasma mode, we obtain quantum-sized free standing alloy nanocrystals with a mean size of 7.3 nm. The presence of Si 1−x Ge x alloy particles is confirmed with multiple techniques, i.e. Raman spectroscopy, XRD (Xray diffraction) and HRTEM (high resolution transmission electron microscopy) studies, with each of these methods consistently yielding the same composition. The nanocrystals synthesized here have potential applications in band-gap engineering for multijunction solar cells. [ABSTRACT FROM AUTHOR]

Open-space nanomaterials are a widespread class of technologically important materials that are generally incompatible with analysis by atom probe tomography (APT) due to issues with specimen preparation, field evaporation and data reconstruction. The feasibility of encapsulating such non-compact matter in a matrix to enable APT measurements is investigated using nanoparticles as an example. Simulations of field evaporation of a void, and the resulting artifacts in ion trajectory, underpin the requirement that no voids remain after encapsulation. The approach is demonstrated by encapsulating Pt nanoparticles in an ZnO:Al matrix created by atomic layer deposition, a growth technique which offers very high surface coverage and conformality. APT measurements of the Pt nanoparticles are correlated with transmission electron microscopy images and numerical simulations in order to evaluate the accuracy of the APT reconstruction. [ABSTRACT FROM AUTHOR]

Abstract: Wurtzite ScAlN nanowires, grown on a scandium nitride (ScN) thin film by hydride vapor phase epitaxy (HVPE), were analyzed by energy dispersive analysis of X-rays (EDX), CL, high resolution transmission electron spectroscopy (HRTEM), and scanning electron microscopy (SEM). The wires were grown along the [0001] axis, had an average length of , a diameter between 50 and 150nm, and a ScAlN composition with a 95:5Al:Sc ratio. Cathodoluminescence studies on the individual wires showed a sharp emission near 2.4eV, originating from the Sc atoms in the aluminum nitride (AlN) matrix. The formation of such a semiconducting ScAlN alloy could present a new alternative to InAlN for optoelectronic applications operating in the 200–550nm range. [Copyright &y& Elsevier]

Abstract: The electrical and physical properties of CeO2–HfO2 nanolaminates deposited by pulsed laser deposition (PLD) are investigated. The properties of the nanolaminates are compared with binary CeO2 and HfO2 thin films. Layers were deposited using CeO2 and HfO2 targets at substrate temperatures between 220 and 620°C in 10Pa Ar+H2 or O2. In situ post deposition anneal (PDA) was achieved by controlled cooling down to room temperature with . Nanolaminates starting with CeO2 show lower EOT and leakage compared to layers starting with HfO2. TEM and XRD analyses showed thickness-dependent crystallinity of the layers, varying from amorphous to highly oriented polycrystalline phase. C–V and I–V measurements were done on the capacitors. Lowest fixed-charge density was found for the nanolaminates deposited at 520°C. The k values of the nanolaminates extracted by the EOT-physical thickness plots were found to be 141, 48 and 22, for deposition temperatures 420, 520 and 620°C, respectively. Higher k value for lower deposition temperatures is explained by the thickness dependent morphology of the layers. An with was found for binary HfO2 layer with 4nm physical thickness. Lowest leakage current density was for a 4nm laminate deposited at 420°C and with a cooling rate of 2°C/min during PDA. [Copyright &y& Elsevier]