Figure 3. Honeycomb lattice of HgTe spheres and its conduction band structure.

(a,b) Top view of an assembly of spheres connected by cylinders, forming a honeycomb lattice of HgTe. Hg atoms are in yellow, Te atoms are in grey. The lattice spacing a, that is, the centre-to-centre distance between neighbour spheres, is equal to the diameter D of the spheres and d is the diameter of the cylinders. (c–e) Conduction band dispersions resulting from the atomistic TB calculation for D=5.0 nm and d/D=0.3 (c), d/D=0.6 (d) or d/D=0.8 (e). Non-trivial gaps are indicated by pink shaded regions. (f) Evolution of the gap between the lowest p bands versus d/D for three values of D (green triangles: D=5.9 nm; blue circles: D=5.0 nm; red crosses: D=4.1 nm).