Crystalline bismuth telluride nanoparticles grown by a magnetically assisted physical method

Abstract

A magnetically assisted physical method was developed to synthesize crystalline bismuth telluride (Bi2Te3) nanoparticles. This method takes advantage of co-sputtering from Bi2Te3 and cobalt (Co) targets at elevated temperatures. Well-faceted polygonal or pyramidal nanoparticles were obtained from co-sputtering at a substrate temperature above 200 degrees C. The nanoparticles were analyzed to have a Bi to Te atomic ratio of 2 to 3, which represents the stoichiometric composition of Bi2Te3, without any detectable Co. The lateral size of Bi2Te3 nanoparticles generally increased in the range of 50-160 nm and their facet structure was better developed as the growth temperature increased. Electron microscopy studies revealed that the Bi2Te3 nanoparticles were distributed on the surface of a growing Bi2Te3 thin film. Both the nanoparticles and the thin film were proven to be highly crystalline by cross-sectional TEM and selected-area electron diffraction patterns. A series of physical mechanisms were proposed to account for this unique growth technique. (C) 2016 Elsevier Ltd. All rights reserved.