HgTe: a potential thermoelectric material in the cinnabar phase.

We present the calculations of the electronic structure and transport properties on the zinc-blende (ZB) and cinnabar phases of HgTe using the full-potential linearized augmented plane-wave method and the semiclassical Boltzmann theory. Our results show that n-doped cinnabar HgTe has a significant larger Seebeck coefficient and electrical conductivity along the z axis than those of the n-doped ZB phase. This is mainly attributed to the large structural anisotropy originated from its chainlike bonding characters along the z axis, resulting in the anisotropic energy distribution in the lowest conduction band of cinnabar structure. The resulting ZT values along the z axis of the n-doped cinnabar HgTe are predicted to reach very high values of 0.61 at room temperature and 1.74 at 600 K. Therefore, the current theory suggests that the cinnabar structure of HgTe could be a good thermoelectric material. Future experiments are thus demanded to explore its thermoelectric performance by making use of the high ZT.