An investigation was made of the structure of the (00•1) basal twin boundary in Bi2Te3. Electron diffraction measurements showed that this interface corresponded to a 180° rotation of the crystal about the [00•1] axis, an alignment that reversed the stacking of the basal planes. The basal planes in the perfect Bi2Te3 structure were arranged in a repeating sequence of five-layer wide Te(1)–Bi–Te(2)–Bi–Te(1) packets. Thus, it was possible for the twin interface to be located at one of three distinct locations: at the Te(2) layer, the Bi layer, or the Te(1) layer. Using aberration-corrected high-angle annular dark field scanning transmission electron microscopy, it was shown that the twin boundary was terminated at the Te(1) layer, where the stacking formed a double-layer of Te. The observations were consistent with ab initio calculations, which predicted this twin termination to have the lowest interfacial energy of the three configurations considered. The calculations and observations also revealed a small expansion in the interplanar spacing at the interface.

Structure of the (0001) Basal Twin Boundary in Bi2Te3. D.L.Medlin, Q.M.Ramasse, C.D.Spataru, N.Y.C.Yang: Journal of Applied Physics, 2010, 108[4], 043517