The electronic behavior of metallic carbon nanotubes under the influence of atomistic vacancy defects present in the channel is theoretically investigated using non-equilibrium Green’s function method self-consistently coupled with three-dimensional electrostatics. A nearest neighbor tight binding model based on a single pz orbital is used for the device Hamiltonian. A single vacancy defect in ...

Owing to their remarkable mechanical properties, carbon nanotubes have been employed in many diverse areas of applications. However, similar to any of the many man-made materials used today, carbon nanotubes (CNTs) are also susceptible to various kinds of defects. Understanding the effect of defects on the mechanical properties and behavior of CNTs is essential in the design of nanotube-based d...

We performed first-principles calculations to reveal the possibility of applying pristine, defective, and B-doped graphene in feasible negative electrode materials of ion batteries. It is found that the barriers for ions are too high to diffuse through the original graphene, however the reduced barriers are obtained by introducing defects (single vacancy, double vacancy, Stone-Wales defect) in ...

Positron annihilation measurements, supported by first-principles electron-structure calculations, identify vacancies and vacancy clusters decorated by 1-2 dopant impurities in highly Sb-doped Si. The concentration of vacancy defects increases with Sb doping and contributes significantly to the electrical compensation. Annealings at low temperatures of 400-500 K convert the defects to larger co...

Perturbed angular correlation of gamma rays (PAC) was applied to measure concentrations of point defects in quenched and milled intermetallic compounds. Two systems with high ordering energies were studied, PdIn and NiAl, with principal results obtained for PdIn. The defects, lattice vacancies and antisite atoms, were detected by quadrupole interactions induced at nuclei of nearby In/Cd probe a...

We have performed density-functional pseudopotential calculations to investigate the electronic structure, atomic configurations, and formation energies of native point defects and impurities in AlN. For the native defects, the nitrogen vacancy has the lowest formation energy in p-type material and the aluminum vacancy has the lowest formation energy in n-type material. Under n-type conditions ...

While nitrogen doping has been investigated extensively in silicon, there is only limited information on its interaction with vacancies germanium, despite most point defect processes germanium being vacancy controlled. Thus, spin polarized density functional theory calculations are used to examine the association of lattice and for comparison silicon. The results demonstrate significant charge ...

We have identified stable fourfold coordinated vacancy clusters Vn 3 n 18 in Si using a combination of metropolis Monte Carlo, tight-binding molecular-dynamics, and density-functional theory calculations. Our calculations show that the small vacancy defects exclusively favor fourfold coordination thermodynamically rather than hexagonal ringlike structure formation, which has widely been adapted...

Dislocations act in semiconductors as combined positron traps, consisting of a shallow precursor state, which is related to regular parts of the dislocation line, and bound vacancy-like defects. The motion of dislocations during plastic deformation generates a high number of point defects. The clustering of vacancies to stable voids is regarded as a primary process of the jog dragging mechanism...

We report first-principles total-energy density-functional theory electronic structure calculations for the neutral and charge states of H intrinsic ~Frenkel pair! and extrinsic ~H vacancy or interstitial! point defects in KH2PO4. The relaxed atomic structures, the formation energy, the ionization energy, and electron and hole affinities for the various defects have been calculated. For the Fre...