Controlled growth of 3D topological insulator BiSb(Te$_{1-y}$Se$_y$)$_3$ nanocrystals by chemical vapor transport
Croissance en phase vapeur de nanocristaux de l'isolant topologique 3D BiSb(Te$_{1-y}$Se$_y$)$_3$
Résumé
The structural and electrical properties of thin nanocrystals of the 3D topological insulator BiSb(Te$_{1-y}$Se$_y$)$_3$ (y = 0.0, 0.01, 0.02,....0.09) have been investigated. The nanostructures were synthesized from a bulk parent BiSb(Te$_{1-y}$Se$_y$)$_3$ polycrystalline powder on different substrate materials using the bottom-up chemical vapor transport method without the addition of transport agents, resulting in well-faceted and thin single crystals with dimensions of ~ 20 µm in length and ~ 20 nm in height. Thermodynamic calculations were performed to optimize the growth process. The chemical composition and morphology of the nanocrystals were analyzed by energy dispersive X-ray spectroscopy, scanning electron microscopy, and atomic force microscopy. The R$\bar{3}$m crystal structure of individual nanocrystals and their high crystalline quality were studied by high-resolution transmission electron microscopy. Magnetotransport measurements confirm that bulk-charge compensation could be achieved by adding a small amount of Se to the ternary compound BiSbTe$_3$, and the transport properties of thin flakes further reveal the enhanced carrier mobility of topological surface-state carriers.
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