Growth of micro-devices of topological insulator thin films by molecular beam epitaxy on substrates pre-patterned with photolithography

In the fabrication of micrometer-sized structures from an epitaxial topological insulator thin film with photolithography, the film is usually deteriorated by the chemicals used in the process. By molecular beam epitaxy of (Bi_xSb_1-x)₂Te₃ topological insulator onto Hall bar-shaped plateaus pre-lithographed on SrTiO₃ substrate, we have directly prepared Hall bar devices of epitaxial topological insulator thin film, avoiding the degradation of film quality in photolithography. Atomic force microscope and transport measurements have demonstrated that the Hall bar devices have the similar properties as that of (Bi_xSb_1-x)₂Te₃ films epitaxied on ordinary SrTiO₃ substrates. The new microfabrication method can not only help to realize various novel quantum phenomena predicted in topological insulators but be applied to other epitaxial low-dimensional systems as well.