Abstract
Physical vapour deposition (PVD) is used to grow millimetre-long Bi2Te3 sub-micron belts catalysed by TiO2 nanoparticles. The catalytic efficiency of TiO2 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 Bi2Te3 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 × 105 S m −1 indicates an excellent sample quality.
Highlights
Bi2Te3 is a well-known thermoelectric and a topological insulator (TI) [1]
A ceramic insert supports the substrates as depicted in Fig. 1b so that their position is right in the vertical centre of the quartz tube in order to optimize the exposure to the vapour
In summary, we have studied the growth of Bi2Te3 submicron belts using TiO2 nanoparticles as catalyst
Summary
Bi2Te3 is a well-known thermoelectric and a topological insulator (TI) [1]. Interest in thermoelectrics is fuelled by the potential to generate power from waste heat [2, 3]. The thermoelectric efficiency is quantified by the figure of merit ZT which is a function of the electrical and thermal conductivity and the Seebeck coefficient of the thermoelectric material. The topologically protected surface transport emerges as a result of strong spin-orbit coupling in Bi2Te3 and other materials [6]. The surface state is formed by a single Dirac cone with linear dispersion and has attracted great interest in the last decade [7].
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