To analyze the local structure and/or chemical states of boron atoms in boron-doped diamond, which can be synthesized by the microwave plasma-assisted chemical vapor deposition method (CVD-B-diamond) and the temperature gradient method at high pressure and high temperature (HPT-B-diamond), we measured the soft X-ray emission spectra in the CK and BK regions of B-diamonds using synchrotron radia...

Impurity scattering properties for optical excitations in boron-nitride (BN) heteropolar nanotubes are investigated theoretically. We extend the continuum k · p model of the carbon nanotubes to that of the BN systems, where site energies are introduced at the boron and nitrogen atoms in order to take account of the strong ionic properties of the BN bonds. We show that the backward scattering co...

Electrical conductivity of a highly boron doped chemical vapor deposited diamond thin film has been studied at different temperatures under high electric field conditions. Current-voltage characteristics have been measured using pulsed technique to reduce thermal effects. Experimental results evidence deep impurity impact ionization avalanche in p-type diamond up to room temperature.

The pristine boron nitride nanotubes have a large direct band gap around 5 eV. This band gap can be engineered by doping. We investigate electronic structure of the doped hexagonal boron nitride (5,5) nanotubes using the linearized augmented cylindrical wave method. In particular, this work focuses on systematical study of the band gap and the density of states around the Fermi-level when the n...

Effect of boron and nitrogen co-doping on the electron field emission properties of the diamond films was examined using current image tunneling spectroscopy in atomic force microscopy (CITS, AFM). Tunneling current-voltage (It-V) characteristics measured by AFM indicate that incorporation of boron and nitrogen species induced the presence of impurity state. Such a characteristic is closely rel...

The influence of different boron precursor powders on the critical current density of MgB2 superconductor with added Ni-Co-B nanoparticles is investigated. Different types of boron have different morphologies, particle sizes and impurity content, all of which have a strong impact on the critical current density ( Jc). The boron samples investigated in this study include three different boron po...

Boron nitride ~BN! thin films ~containing mixed cBN/hBN phase! have been deposited on Si~100! substrates using neutralized nitrogen beam and electron beam evaporation of boron. All as-deposited BN films were p type with a room-temperature carrier concentration in the range of 5310 to 1310 cm. The Mg-doped BN films showed carrier concentrations in the range of 1.2 310 cm to 5.2310 cm when the Mg...

Density profiles for a light impurity, boron, are reported for internal transport barrier (ITB) discharges in Alcator C-Mod. During the ITB, the light impurity gradient steepens because the impurity pinch increases relative to diffusion. The ITB-induced impurity profile steepening is at approximately the same major radius as that for the main-ion profile. Neoclassical transport does not describ...

Temporally and spatially resolved measurements of carbon and boron impurity density are obtained in the reversed field pinch (RFP) for the first time. It is observed that, unlike in tokamaks and stellarators, the RFP does not exhibit a centrally peaked impurity profile in either standard plasmas where field lines have some degree of stochasticity, or improved confinement discharges where there ...