The sources of neutrals at the outer midplane of the plasma are discussed. We find that both the flux of neutrals escaping the divertor through leaks and ion recycling at main chamber surfaces appear to contribute. The ion flux to the walls is larger than the flux entering the divertor and comparable to recycling at the divertor plate. The cause of these high wall ion fluxes is an enhancement o...

Alloys of GaN, InN and AlN provide an ideal host with a wide range of the electronic bandgap but it is due to the control of impurities that allows to form devices. The role of unintentional impurities becomes especially important when their role as dopants is not established and their incorporation remains undetected. Oxygen concentrations up to some 10 cm are present in any high purity GaAs, ...

Recently, a high-mobility surface conduction channel and in-gap states were identified in the correlated small-gap semiconductor FeSi using electrical transport measurements high-resolution tunneling spectroscopy. The mobility of charge carriers is quantitatively reminiscent topological insulators, but displays lack sensitivity to presence ferromagnetic impurities as studied by means series sin...

The question of anomalous transport due to a band of impurity states in unconventional superconductors is discussed. In general, the bound state energies are not in midgap, even in the unitarity limit. This implies that, generically, the states associated with impurities are broad resonances, not true bound states. There is no impurity band in the usual sense of the phrase. The wavefunctions of...

We present a floating-potential dielectrophoresis method used for the first time to achieve controlled alignment of an individual semiconducting or metallic single-walled carbon nanotube (SWCNT) between two electrical contacts with high repeatability. This result is significantly different from previous reports, in which bundles of SWCNTs were aligned between electrode arrays by a conventional ...

We present a first-principles study of the evolution of the mechanical and transport properties of clean and contaminated Au nanowires during the whole breaking process. We combine density functional theory total energy calculations and Keldysh Green’s function methods in order to determine the changes in the structure and conductance induced by the presence of hydrogen and oxygen atomic impuri...

Doping is extremely important for controlling the electronic conductivity of bulk semiconductors. However, very few examples exist where impurities that have been incorporated into colloidal semiconductor nanocrystals affect their electronic properties. Here we will discuss the challenges in this area as well as recent progress. In particular, we will describe an approach to lightly dope semico...

One of the most important physical parameters to describe the quality of a piece of semiconductor material is the electron scattering length le. Also referred to as the mean-free path, it stands for the average distance between the randomly distributed scatterers in the material, such as lattice defects, impurities, and phonons. The electron mean-free path is typically a few nanometers (1 nm = ...

1. Overview The main research topics for this year have been organized in nine milestones with theoretical and experimental relevance: 1. Influence of the collisions in the gyrokinetic simulations on the particle transport 2. Characterization of the intermittent events and particle transport on the plasma boundary 3. Characterization of long-range correlations and multi-scale physics in L-mode ...

Strongly peaked impurity density profiles have been observed in Alcator C after frozen hydrogen pellet injection. More recent experiments in ASDEX, PBX, TEXT, JET, and TFTR have exhibited similar impurity accumulation during regimes of improved confinement. In this context, we present calculations of the neoclassically predicted equilibrium profiles of the intrinsic impurities in Alcator C. The...