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In situ low-energy electron microscopy is used to investigate the near-equilibrium dynamics of surface-terminated dislocations during annealing of atomically smooth TiN(111) layers at temperatures between 1600 and 1735 K. At each temperature the nucleation and growth of spiral steps rotating around dislocation cores is observed.

We investigate the impact of structure relaxation on the upper performance of a silicon nanowire metal-oxide-semiconductor field-effect-transistor (MOSFET) with small diameter employing a semiclassical transport model to calculate its ballistic I-V characteristics. For wires along the lang110rang axis and 1 nm diameter, structure relaxation induces large changes in the bond length of silicon atoms at the surface (~33%). Despite these bond length variations, the effect of reconstruction on the ballistic ON-current of Si-NW MOSFETs turns out negligible in the case considered, which can be attributed to an only slight variation of the electron effective mass after reconstruction [ABSTRACT FROM PUBLISHER]

NbC x N 1− x layers were deposited on MgO(001) by reactive magnetron co-sputtering from Nb and graphite targets in 5 mTorr pure N 2 at T s = 600–1000 °C. The anion-to-Nb ratio of 1.09 ± 0.05 is independent of T s and indicates a nearly stoichiometric rock–salt structure Nb(N,C) solid solution. In contrast, the C-to-N ratio increases from 0.20–0.59 for T s = 600–1000 °C, which is attributed to a low C sticking probability at high N surface coverage at low T s . Layers grown at T s ≥ 700 °C are epitaxial single-crystals with a cube-on-cube relationship to the substrate, (001) NbCN ||(001) MgO and [100] NbCN ||[100] MgO , as determined from X-ray diffraction θ –2 θ and ϕ -scans. Reciprocal space mapping on a NbC 0.37 N 0.63 layer deposited at T s = 1000 °C indicates an in-plane compressive strain of − 0.4% and a relaxed lattice constant of 4.409 ± 0.009 Å. The lattice constant of NbC x N 1− x increases with x , consistent with a linear increase predicted by first-principles density functional calculations. The calculated bulk modulus, 307 GPa for NbN and 300 GPa for NbC, is nearly independent of x . Similarly, c 11 increases slightly from 641 to 666 GPa, but c 12 decreases considerably from 140 to 117 GPa, and c 44 more than doubles from 78 to 171 GPa as x increases from 0 to 1, indicating a transition from ductile NbN to brittle NbC. This also results in an increase in the predicted isotropic elastic modulus from 335 to 504 GPa, which is in good agreement with the measured 350 ± 12 GPa for NbC x N 1− x (001) with x = 0.19–0.31. The hardness H = 22 ± 2 GPa of epitaxial NbC x N 1− x layers is nearly independent of x = 0.19–0.37 and T s = 700–1000 °C, but is reduced to H = 18.2 ± 0.8 GPa for the nanocrystalline layer deposited at T s = 600 °C. The electrical resistivity decreases strongly with increasing T s < 800 °C, due to increasing crystalline quality, and is 262 ± 21 μΩ-cm at room temperature and 299 ± 22 μΩ-cm at 77 K for T s ≥ 800 °C, indicating weak carrier localization due to the random distribution of C atoms on anion sites. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ab initio modeling of kesterite phase for full range of Cu2ZnSn(S x Se1−x)4 was done. [•] Lattice constants increase with the decrease of S/Se ratio. [•] All elastic constants and moduli except C16 decrease with the decrease of S/Se ratio. [•] Poisson’s ratio stays the same with the decrease of S/Se ratio. [Copyright &y& Elsevier]

Abstract: Several III-VI body-centered tetragonal layered compounds belonging to space group I41/amd have been a subject of interest recently because of their potential applications in high efficiency and environmentally friendly copper–indium–gallium–selenide solar cells and molecules. Here we have studied the structural, energetic, and electronic properties of four compounds β-In2X3 (X=O, S, Se, Te), in this space group. Using first principles computations, we have fully determined the lattice constants a and c, as well as 10 internal parameters that define this unique structure of primitive unit cells of 40 atoms. For β-In2S3 our computed values are found to be consistent with experimental measurements. The bulk modulus B, local electronic density of states, total density of states, and band gap Eg of these phases have been investigated. [Copyright &y& Elsevier]