Free-standing millimetre-long Bi(2)Te(3) sub-micron belts catalyzed by TiO(2) nanoparticles

Physical vapour deposition (PVD) is used to grow millimetre-long Bi(2)Te(3) sub-micron belts catalysed by TiO(2) nanoparticles. The catalytic efficiency of TiO(2) nanoparticles for the nanostructure growth is compared with the catalyst-free growth employing scanning electron microscopy. The catalyst-coated and catalyst-free substrates are arranged side-by-side, and overgrown at the same time, to assure identical growth conditions in the PVD furnace. It is found that the catalyst enhances the yield of the belts. Very long belts were achieved with a growth rate of 28 nm/min. A ∼1-mm-long belt with a rectangular cross section was obtained after 8 h of growth. The thickness and width were determined by atomic force microscopy, and their ratio is ∼1:10. The chemical composition was determined to be stoichiometric Bi(2)Te(3) using energy-dispersive X-ray spectroscopy. Temperature-dependent conductivity measurements show a characteristic increase of the conductivity at low temperatures. The room temperature conductivity of 0.20 × 10(5) S m (−1) indicates an excellent sample quality.