High zT and Its Origin in Sb-doped GeTe Single Crystals.

ABSTRACT: A record high zT of 2.2 at 740 K is reported in Ge_0.92Sb_0.08Te single crystals, with an optimal hole carrier concentration ≈4 × 10²⁰ cm^-3 that simultaneously maximizes the power factor (PF) ≈56 µW cm^-1 K^-2 and minimizes the thermal conductivity ≈1.9 Wm^-1 K^-1. In addition to the presence of herringbone domains and stacking faults, the Ge_0.92Sb_0.08Te exhibits significant modification to phonon dispersion with an extra phonon excitation around ≈5-6 meV at Γ point of the Brillouin zone as confirmed through inelastic neutron scattering (INS) measurements. Density functional theory (DFT) confirmed this phonon excitation, and predicted another higher energy phonon exc

SUBMITTER: Vankayala RK 

PROVIDER: S-EPMC7740100 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature