Designer Topological Insulator with Enhanced Gap and Suppressed Bulk Conduction in BiSe/SbTe Ultrashort-Period Superlattices.

A novel approach to suppress bulk conductance in three-dimensional (3D) topological insulators (TIs) using short-period superlattices (SLs) of two TIs is presented. Evidence for superlattice gap enhancement (SGE) was obtained from the reduction of bulk background doping from 1.2 × 10 cm to 8.