Van der Waals Epitaxy of Millimeter-Domain Bi2Se3

The unique electronic structure of Bi2Se3 makes it appealing not only for studying fundamental topological physics but also for pursuing technological applications that include future electronics, spintronics, and quantum computing. This work uses a chemical vapor deposition approach to synthesize sub-millimeter domain continuous epitaxial thin films as well as continuous films with preferred orientation and domain sizes ranging up to a millimeter. Atomic force microscopy imaging reveals a terraced pyramid structure with step sizes down to one quintuple layer. We observe that large amounts of deposition on the tube walls from previous growths negatively affect the quality of epitaxy but positively affect grain size due to re-vaporization of previous growth. Transport measurements and Hikami-Larkin-Nagaoka fits of conductivity vs magnetic field indicate a bulk conducting nature to the film. This work pushes forward the domain size Bi2Se3 films by an order of magnitude, while maintaining the regularly reported doping problems of topological insulators.