Silicon nanotubes (SiNTs) have been grown on a porous alumina surface, without the assistance of catalysts, by molecular beam epitaxy (MBE). The flow rate of Si atoms and the corrugated porous alumina surface seem to play an important role in the continuous growth of Si tubular structures. The Figure shows a field‐emission scanning electron microscopy image of the SiNTs grown on a regular array of hexagonal porous alumina.

No abstract

Si 1−x C x alloys have been studied using self-consistent-charge density-functional-based tight-binding calculations. The origin of experimentally observed carbon-induced vibrational peaks near 475, 607 and 810 cm −1 are analysed, based on the theoretical calculations. The stability, vibrational frequencies, lattice relaxations, and energy gap variances of substitutional, interstitial single-carbon and dicarbon complexes in crystalline silicon are calculated. All the impurities induce severe lattice relaxations of adjacent Si atoms. The peak near 475 cm −1 originates from the lattice relaxations of Si atoms up to second-nearest neighbours from carbon impurities in all cases. The peak near 605 cm −1 originates mainly from the midbond interstitial carbon (which is at odds with general belief) whereas the high-energy peaks near 810 cm −1 result from the formation of the carbon complexes.

No abstract