The Electronic Band Structure of Bismuth Telluride

The electronic energy levels of Bi2Te3 at symmetry points in the Brillouin zone are classified. An augmented plane waves calculation is carried out to try to determine the possible positions and symmetries of the band edges. The calculation is not self-consistent and several approximations are made in evaluating the potential. It is found that an energy gap arises essentially because of spin-orbit interaction. The bottom of the conduction band, of p-type symmetry, appears to be at or near the centre of the four-sided faces of the Brillouin zone. The valence band appears to have several extrema. Since the experimental evidence so far is weak, the main value of these theoretical conclusions is as a framework for the interpretation of future experimental results.