Abstract: A major problem with most of the present nuclear reactors is their safety in terms of the release of radioactivity into the environment during accidents. In some of the future nuclear reactor designs, i.e. Generation IV reactors, the fuel is in the form of coated spherical particles, i.e. TRISO (acronym for triple coated isotropic) particles. The main function of these coating layers is to act as diffusion barriers for radioactive fission products, thereby keeping these fission products within the fuel particles, even under accident conditions. The most important coating layer is composed of polycrystalline 3C–SiC. This paper reviews the diffusion of the important fission products (silver, caesium, iodine and strontium) in SiC. Because radiation damage can induce and enhance diffusion, the paper also briefly reviews damage created by energetic neutrons and ions at elevated temperatures, i.e. the temperatures at which the modern reactors will operate, and the annealing of the damage. The interaction between SiC and some fission products (such as Pd and I) is also briefly discussed. As shown, one of the key advantages of SiC is its radiation hardness at elevated temperatures, i.e. SiC is not amorphized by neutrons or bombardment at substrate temperatures above 350 °C. Based on the diffusion coefficients of the fission products considered, the review shows that at the normal operating temperatures of these new reactors (i.e. less than 950 °C) the SiC coating layer is a good diffusion barrier for these fission products. However, at higher temperatures the design of the coated particles needs to be adapted, possibly by adding a thin layer of ZrC.

Abstract: Carbon diffusion barriers are introduced as a general and simple method to prevent premature carbon dissolution and thereby to significantly improve graphene formation from the catalytic transformation of solid carbon sources. A thin Al2O3 barrier inserted into an amorphous-C/Ni bilayer stack is demonstrated to enable growth of uniform monolayer graphene at 600 °C with domain sizes exceeding 50 μm, and an average Raman D/G ratio of <0.07. A detailed growth rationale is established via in situ measurements, relevant to solid-state growth of a wide range of layered materials, as well as layer-by-layer control in these systems.

Abstract: A method for semiconductor fabrication includes forming at least one of a diffusion barrier layer and a metal containing layer over a dielectric layer in a gate cavity. A first anneal is performed to diffuse elements from the at least one of the diffusion barrier layer and the metal containing layer into the dielectric layer. The metal containing layer and the diffusion barrier layer are removed. A second anneal is performed to adjust diffusion of the elements in the dielectric layer to provide a gate dielectric region.

Abstract: Using first principles calculations based on density functional theory, the adsorption and diffusion properties of Li and Mg atoms on single-layered and bulk V2O5 are investigated. The simulation results show that the diffusion barrier of Li on the single-layered V2O5 is decreased compared with that of the bulk V2O5, which indicates that the Li mobility can be significantly enhanced on the single-layered V2O5. The increased binding energies of Li to single-layered V2O5 make them more attractive for promising cathode materials. Although the diffusion barrier of Mg on the single-layered V2O5 does not decrease, the binding energies of Mg to single-layered V2O5 is increased compared with that of bulk V2O5, thus the single-layered V2O5 is an attractive cathode material for rechargeable ion batteries.

Abstract: The diffusion process of He in W is simulated by a molecular dynamics (MD) method with self-developed W–H–He analytic bond-order potentials. The mean squared displacement (MSD) method is employed to determine diffusivity at different temperatures, and then the diffusivity–temperature (D–T) relationship is fitted by the Arrhenius equation to obtain the prefactor and the diffusion barrier. We show the diffusivity of He and the corresponding prefactor and diffusion barrier are different at different temperature ranges. The diffusivities are 9.50 × 10−9 exp(−0.021 eV/kT) m2/s in the temperature range of 50–300 K, 3.61 × 10−8 exp(−0.057 eV/kT) m2/s in 300–1500 K, and 8.562 × 10−8 exp(−0.157 eV/kT) m2/s in 1500–3000 K, respectively, which correspond to different diffusion mechanisms. At a lower temperature, He diffuses directly from one tetrahedral interstitial site (TIS) to another TIS through the diagonal interstitial site with a lower diffusion barrier, while it can diffuse from one TIS to other TIS through the octahedral interstitial site with higher barrier at higher temperature.

Abstract: The adsorption and diffusion of lithium on silicene are studied by using the first-principles method. It is found that the adsorption energy of Li adsorbing on silicene is significantly larger than that of Li adsorbing on graphene. With the increasing concentration of adsorbed Li atoms, the adsorption energy also increases. The diffusion barrier of Li on silicene is relatively low, which is insensitive to the concentration of adsorbed atoms.

Abstract: An apparatus including a near field transducer positioned adjacent to an air bearing surface, the near field transducer including an electrically conductive nitride; a first magnetic pole; and a heat sink, a diffusion barrier layer, or both positioned between the first magnetic pole and the near field transducer, wherein the heat sink, the diffusion barrier or both include rhodium (Rh) or an alloy thereof; ruthenium (Ru) or an alloy thereof titanium (Ti) or an alloy thereof tantalum (Ta) or an alloy thereof tungsten (W) or an alloy thereof borides; nitrides; transition metal oxides; or palladium (Pd) or an alloy thereof.

Abstract: A metallic dopant element having a greater oxygen-affinity than copper is introduced into, and/or over, surface portions of copper-based metal pads and/or surfaces of a dielectric material layer embedding the copper-based metal pads in each of two substrates to be subsequently bonded. A dopant-metal silicate layer may be formed at the interface between the two substrates to contact portions of metal pads not in contact with a surface of another metal pad, thereby functioning as an oxygen barrier layer, and optionally as an adhesion material layer. A dopant metal rich portion may be formed in peripheral portions of the metal pads in contact with the dopant-metal silicate layer. A dopant-metal oxide portion may be formed in peripheral portions of the metal pads that are not in contact with a dopant-metal silicate layer.

Abstract: A CeO2 dispersed δ-Ni2Al3 was formed by partially aluminizing an electrodeposited Ni film containing CeO2. The aluminide/Ni–CeO2 coating system itself quickly formed a CeO2-rich diffusion barrier between aluminide and Ni during annealing in vacuum at 1000 °C. A model for the formation of the diffusion barrier was proposed, based on the characterization of the evolution with time of the phase compositions of the aluminide at the interface.

Abstract: Coatings with a high amount of MAX phase were obtained onto Ti substrate using the pulsed electrospark deposition (PED) technique and Cr 2 AlC electrode material (ЕМ). The structure and phase formation of the coatings generated at different modes were studied. It was found, that a layer of titanium carbide was formed during the initial stage of the deposition at the interface as a result of chemical reaction between Cr 2 AlC electrode and Ti substrate which further acts as a diffusion barrier.

Abstract: Multicomponent high-entropy nitrides have been attempted as robust diffusion barrier materials to inhibit the severe interdiffusion of Cu and Si; however, the improvement in their diffusion resistance relative to the abilities of few-component nitrides has actually not been verified. Thus, in this study, nitride barriers with different numbers of components (metallic elements), from unitary TiN to senary high-entropy (TiTaCrZrAlRu)N (with the same face-centered cubic structure and a thickness of 5 nm), were prepared. The failure of these nitride barriers in resisting the interdiffusion of Cu and Si was examined, and the activation energy of Cu diffusion through the nitrides was determined. With more components incorporated, the failure temperature of the nitrides was found to markedly increase from 550°C to 900°C, and the activation energy of Cu diffusion was effectively raised from 107 kJ/mol to 161 kJ/mol. Severe lattice distortions and random cohesions are suggested as the dominant factors for the improved diffusion-resistant ability of the multicomponent high-entropy nitrides.

Abstract: Thin and defect-free supported palladium membranes were prepared on macroporous α-alumina ceramic tubes using TS-1 zeolite as the intermediate and diffusion barrier layer. It is necessary to modify the pore size of the substrate and form an effective diffusion barrier between the palladium membrane and the support in order to obtain a continuous and thin Pd layer. The detailed microstructure of the composite membranes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy. Pd membranes supported on a TS-1 layer with a thickness of 2–5 μm showed high H2 flux and ideal selectivity of H2/N2 in the working temperature range. The result reveals that the palladium penetrated into the TS-1 films through the nonzeolitic pores existing in the zeolite films. The resultant Pd-TS-1 membrane displays very high stability due to the excellent anchorage of Pd layer inside the zeolite barrier grown on the support. This membrane could be able to tolerate rapid and repeated cycling of gases, temperature and pressure without sacrificing its good permeance and selectivity, even below the Pd embrittlement temperature (<573 K). These results suggest that TS-1 zeolite is an effective intermediate substrate modifier to bridge the large pore size of the support for the synthesis of a thin Pd layer.

Abstract: Flexible Cu(In,Ga)Se2 (CIGS) solar cells on stainless steel foils face the problem of efficiency deterioration when iron impurities diffuse into the absorber layer. The influence of the magnetron sputtering conditions and the design of Mo-based back contacts on the property of the diffusion barrier against iron is reported here for high efficiency CIGS solar cells grown at low substrate temperatures (Tmax = 475 °C). The overall material density of the Mo back contact was identified as the dominant parameter for the impurity diffusion barrier performance. It was found that this is also true for Mo bilayer contacts, which show enhanced film densities at low residual stress. The iron diffusion profile in the back contact and CIGS was measured by secondary ion mass spectroscopy, where a linear decrease in the iron impurity concentration in the CIGS towards the CdS buffer layer was found. Furthermore, this iron distribution in CIGS and its consequences on the solar cell efficiency is discussed, supported by defect analysis measurements and photovoltaic device simulations. With a stress-free ∼500 nm thick Mo bilayer back contact, best solar cell efficiencies above 15% were achieved with antireflection coating.

Abstract: A polarizing element includes a transparent substrate, a reflective layer constituting, on the transparent substrate, grid-shaped convexities arrayed at a pitch smaller than a wavelength in a used optical bandwidth, a dielectric layer formed on the reflective layer, a diffusion barrier layer formed on the dielectric layer, and an absorbing layer formed on the diffusion barrier layer such that the diffusion barrier layer is sandwiched between the absorbing layer and the dielectric layer. This polarizing element has an excellent optical property and is able to prevent mixing of the absorbing layer and the dielectric layer under a high temperature.

Abstract: We report the XPS characterization of a thin film of Al2O3 (35 nm) deposited via e-beam evaporation onto silicon (100). The film was characterized with monochromatic Al Kα radiation. An XPS survey scan, an Al 2p narrow scan, an O 1s narrow scan, and the valence band spectrum were collected. The Al2O3 thin film is used as a diffusion barrier layer for templated carbon nanotube (CNT) growth in the preparation of microfabricated thin layer chromatography plates.

Abstract: A high dielectric constant (high-k) gate dielectric layer is formed on semiconductor fins including one or more semiconductor materials. A patterned diffusion barrier metallic nitride layer is formed to overlie at least one channel, while not overlying at least another channel. A threshold voltage adjustment oxide layer is formed on the physically exposed portions of the high-k gate dielectric layer and the diffusion barrier metallic nitride layer. An anneal is performed to drive in the material of the threshold voltage adjustment oxide layer to the interface between the intrinsic channel (s) and the high-k gate dielectric layer, resulting in formation of threshold voltage adjustment oxide portions. At least one workfunction material layer is formed, and is patterned with the high-k gate dielectric layer and the threshold voltage adjustment oxide portions to form multiple types of gate stacks straddling the semiconductor fins.