Transport Properties of Cubic Crystalline Ge${}_2$Sb${}_2$Te${}_5$: A Potential Low-temperature Thermoelectric Material

Ge${}_2$Sb${}_2$Te${}_5$ (GST) has been widely used as a popular phase change material. In this study, we show that it exhibits high Seebeck coefficients 200

• 300 $\mu$V/K in its cubic crystalline phase ($c$-GST) at remarkably high $p$-type doping levels of $\sim$ 1$\times$10${}^{19}$ - 6$\times$10${}^{19}$ cm${}^{-3}$ at room temperature. More importantly, at low temperature (T = 200 K), the Seebeck coefficient was found to exceed 200 $\mu$V/K for a doping range 1$\times$10${}^{19}$ - 3.5$\times$10${}^{19}$ cm${}^{-3}$. Given that the lattice thermal conductivity in this phase has already been measured to be extremely low ($\sim$ 0.7 W/m-K at 300 K),\citep{r51} our results suggest the possibility of using $c$-GST as a low-temperature thermoelectric material.