Papers by Author: A. Miranda

Abstract: The effects on the electronic band structure of hydrogenated cubic silicon carbide (-SiC) nanowires of changes in the diameter and morphology are studied using a semiempirical sp3s* tight-binding approach applied to a supercell model. The results of the calculation of the electronic band structure and electronic density of states obtained are compared with those calculated by density functional theory within local density approximation only for the bulk of -SiC. As boundary conditions, we passivated all the Si and C dangling bonds with hydrogen atoms. The results show that although surface morphology modifies the band gap, the change is more systematic with the thickness variation. The energy band gap increases with decreasing diameter in all cases because of quantum confinement, but the scaling is dependent on the morphology (cross-section) of the -SiC nanowires. Finally, the calculations show a consistent asymptotical behavior to the crystalline limit when the width of the wires enlarges.

Abstract: In this work, the effects of the diameter and morphology on the electronic band structure of hydrogenated cubic silicon carbide (b-SiC) nanowires is studied by using a semiempirical sp3s* tight-binding (TB) approach applied to the supercell model, where the Si- and C-dangling bonds on the surface are passivated by hydrogen atoms. Moreover, TB results (for the bulk) are compared with density functional calculations in the local density approximation. The results show that though surface morphology modifies the band gap, the change is more systematic with the thickness variation. As expected, hydrogen saturation induces a broadening of the band gap energy because of the quantum confinement effect.