[en] Experimental/ ab initio calculations ; binding energy ; density functional theory ; effective mass ; elemental semiconductors ; germanium ; Ge-Si alloys ; nanowires ; passivation ; semiconductor heterojunctions ; semiconductor quantum wires ; silicon/ core-shell nanowires ; electronic devices ; first-principles plane wave calculations ; density functional theory ; generalized gradient approximation ; structural properties ; electronic properties ; H-passivated nanowires ; surface passivation ; substitutional effects ; binding energy ; band structure ; effective mass ; quantum confinement ; surface effects ; relative contribution ; size 0.6 nm to 2.9 nm ; Ge-GeSi ; Ge-Si/ A6146 Structure of solid clusters, nanoparticles, nanotubes and nanostructured materials A7115A Ab initio calculations (condensed matter electronic structure) A7115M Density functional theory, local density approximation (condensed matter electronic structure) A8160C Surface treatment and degradation in semiconductor technology A6150L Crystal binding A7125J Effective mass and g-factors (condensed matter electronic structure) A7125R Electronic structure of crystalline elemental semiconductors A7125T Electronic structure of crystalline semiconductor compounds and insulators B2550E Surface treatment (semiconductor technology) B2520C Elemental semiconductors B2520M Other semiconductor materials/ size 6.0E-10 to 2.9E-09 m/ Ge-GeSi/int GeSi/int Ge/int Si/int GeSi/bin Ge/bin Si/bin Ge/el ; Ge-Si/int Ge/int Si/int Ge/el Si/el
[en] Germanium/Germanium-Silicon core/shell nanowires are expected to play an important role in future electronic devices. We use first-principles plane-wave calculations within density-functional theory in the generalized gradient approximation to investigate the structural and electronic properties of bare and H-passivated Ge nanowires and core/shell Ge/Ge-Si, Ge/Si, and Si/Ge nanowires. The diameters of the nanowires considered are in the range of 0.6-2.9 nm and oriented along  and  directions. The diameter, the surface passivation, and the substitutional effects on the binding energy, band structure, and effective mass are extensively investigated considering the relative contribution of quantum confinement and surface effects.