Topological Insulator Nanostructures and Devices

Abstract

We present a series of experiments developing the compounds Bi2Te3, Bi2Se3, and Bi2Te2Se for nanoscale device applications. New metal organic chemical vapor deposition techniques are employed to make high quality mesoscopic samples, focusing on the growth of nanowires and nanotubes with controlled structure and composition. Fundamental properties of nanowires are studied via transmission electron microscopy and magnetotransport experiments at low temperatures. We describe a method for promoting the self-assembly of pristine nanotubes of Bi2Te3, which have not been observed before. Finally, we demonstrate a method of introducing ferromagnetism precisely at the Bi2Te3 surface by developing the epitaxy of Bi2Te3 on the ferromagnetic insulator Cr2Ge2Te6 and we study the hall effect in these new heterostructures at low temperature. Our results are promising for the development of advanced thermoelectric, optoelectronic, or magnetoresistive devices based on the unique properties of these materials, as well as for the realization of new states of matter, such as the quantum anomalous hall state and Majorana fermion states in heavy element nanowires.