Electronic structure and electron mobility in Si_1– xGe_x nanowires

We investigate the electronic structure and the electron mobility in Si_1– xGe_x nanowires for relevant orientations (⁠$⟨001⟩, ⟨110⟩$⁠, and $⟨111⟩$⁠) and diameters up to 8 nm based on atomistic models. The calculation of the electronic structure with random distribution of alloy atoms is compared to the virtual crystal approximation. The electronic properties such as the effective mass and the character of the lowest conduction subband are linked with the strong variations of the phonon-limited electron mobility with varying Ge concentrations. The effect of alloy disorder on the mobility is also discussed.