Electronic structure of β-As₂Te₃

We present calculations of the electronic structure of Bi ₂Te₃-structure type (R3̄m) β-As ₂Te₃ using the state-of-the-art full potential linearized augmented plane wave method implemented in the WIEN2K code. Bi ₂Te₃-structure type arsenic telluride, which forms when monoclinic arsenic telluride is quenched from high temperatures or compressed, is found to be a direct gap semiconductor with ε_g = 0.12 eV. We also calculated the electronic structure of Bi₂Te₃ using the same method for comparison. In contrast to earlier calculations, we optimized the lattice parameters within density functional theory. The lowest conduction band and highest valence band of β-As₂Te₃ are similar to those of Bi₂Te₃ over much of the Brillouin zone, but exhibit a modest difference at the Γ point. β-As ₂Te₃ will likely have a large thermoelectric power in view of its similarity to Bi₂Te₃, including the presence of six-fold degenerate band edges.