Electronic band structure of high‐index silicon nanowires

We calculated the electronic properties of high‐index free‐standing silicon nanowires. [112 ] nanowires are indirect semiconductors for diameters down to 0.8 nm; [110] wires have a direct band gap at the Γ‐point, but the density of states is very small at the conduction band edge. Confinement arguments show that only [001] nanowires are expected to develop a direct gap with a large density of electronic states at the band edges for diameters in the nm range. The magnitude of the gap depends strongly on the wire growth direction, which is due to the different effective confinement length and effective masses for the Γ X‐derived silicon states. Correcting for the extension of the wave functions we find our calculated energies to agree with recent scanning tunneling experiments. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)