Hydrogenated amorphous silicon deposited under accurately controlled ion bombardment using pulse-shaped substrate biasing

We have applied pulse-shaped biasing to the expanding thermal plasma deposition of hydrogenated amorphous silicon at substrate temperatures ? 200?°C and growth rates around 1 nm/s. Substrate voltage measurements and measurements with a retarding field energy analyzer demonstrate the achieved control over the ion energy distribution for...

Quasifree Mg–H thin films

The thermodynamics of hydrogen absorption in Pd-capped Mg films are strongly dependent on the magnesium thickness. In the present work, we suppress such dependency by inserting a thin Ti layer between Mg and Pd. By means of optical measurements, we show that the surface energy contribution to the destabilization of MgH2 is negligible. The...

On the surface roughness development of hydrogenated amorphous silicon deposited at low growth rates

The surface roughness evolution of hydrogenated amorphous silicon (a-Si:H) films has been studied using in situ spectroscopic ellipsometry for a temperature range of 150–400?°C. The effect of external rf substrate biasing on the coalescence phase is discussed and a removal/densification of a hydrogen-rich layer is suggested to explain the...

Positron depth profiling of the structural and electronic structure transformations of hydrogenated Mg-based thin films

We report positron depth-profiling studies on the hydrogen sorption behavior and phase evolution of Mg-based thin films. We show that the main changes in the depth profiles resulting from the hydrogenation to the respective metal hydrides are related to a clear broadening in the observed electron momentum densities in both Mg and Mg2Ni films....

Hydrogen mediated transport of Sn to Ru film surface

The authors report on the interaction of atomic hydrogen with Sn and thin Ru film at room temperature. The study is done using a combination of photoelectron and low energy ion scattering spectroscopies as well as scanning electron microscopy. The adsorption of hydrogen on a Sn surface leads to the formation of stannane (SnH4), which...

Determination of the mobility gap of intrinsic ?c-Si:H in p-i-n solar cells

Microcrystalline silicon (?c-Si:H) is a promising material for application in multijunction thin-film solar cells. A detailed analysis of the optoelectronic properties is impeded by its complex microstructural properties. In this work we will focus on determining the mobility gap of ?c-Si:H material. Commonly a value of 1.1?eV is found, similar...

Hydrogen vacancies facilitate hydrogen transport kinetics in sodium hydride nanocrystallites

We report ab initio calculations based on density-functional theory, of the vacancy-mediated hydrogen migration energy in bulk NaH and near the NaH(001) surface. The estimated rate of the vacancy mediated hydrogen transport, obtained within a hopping diffusion model, is consistent with the reaction rates of H-D exchange in nano-NaH at the...

Xylose anaerobic conversion by open-mixed cultures

Xylose is, after glucose, the dominant sugar in agricultural wastes. In anaerobic environments, carbohydrates are converted into volatile fatty acids and alcohols. These can be used as building blocks in biotechnological or chemical processes, e.g., to produce bioplastics. In this study, xylose fermentation by mixed microbial cultures was...

Bulk Electricity Sea Transport from Remotely Located Power Plants

Electricity is one of the most utilized energy carriers for energy transmission in the world. In recent years more electricity is generated from renewable energy sources. The main drawback of renewable energy sources is that renewable energy power plants are often connected to certain locations. Sometimes these renewable energy power plants are...

Opportunities and limitations of hydrogen storage in zeolitic clathrates

The feasibility of using zeolites, and more specifically the clathrasil subgroup, for hydrogen storage has been investigated by comparing their H2 loading rate and storage capacity to the technically required values. The uptake rate and capacity are determined by means of computational modelling for a large number of clathrasil structures. It...

Incoherent neutron-scattering determination of hydrogen content: Theory and modeling

Hydrogen concentrations of 0 up to 350?mg/kg in a titanium alloy have been determined at National Institute of Standards and Technology (NIST) with neutron incoherent scattering (NIS) and with cold neutron prompt gamma activation analysis. The latter is a well-established technique, while the former was demonstrated earlier at NIST by counting...

A hydrogen ice cube

Hydrogen is considered to be a highly promising energy carrier. Nonetheless, before hydrogen can become the fuel of choice for the future a number of slight problems will have to be overcome. For example, how can hydrogen be safely stored? Motor vehicles running on hydrogen may be clean in concept but where can we put the hydrogen? For many...

Polymeric amorphous carbon as p-type window within amorphous silicon solar cells

Amorphous carbon (a-C) has been shown to be intrinsically p-type, and polymeric a-C (PAC) possesses a wide Tauc band gap of 2.6 eV. We have replaced the p-type amorphous silicon carbide layer of a standard amorphous silicon solar cell with an intrinsic ultrathin layer of PAC. The thickness of the p layer had to be reduced from 9 to 2.5 nm in...

Hydrogen interactions with silicon-on-insulator materials

The booming of microelectronics in recent decades has been made possible by the excellent properties of the Si/SiO2 interface in oxide on silicon systems.. This semiconductor/insulator combination has proven to be of great value for the semiconductor industry. It has made it possible to continuously increase the number of transistors per chip...

The design of a 1330 ktonnes per year low-energy catalytic reformer

Hydrogen absorption in iron and steel during gas tungsten arc welding

Compressibility and fugacity of gaseous hydrogen

The concept of fugacity is explained. Application of compressibility and fugacity data in hydrogen embrittlement calculations is discussed. Equations of state are reviewed. Compressibility factors and fugacity coefficients are calculated. A best estimate is proposed.