Enhancing thermoelectric performance of GeTe monolayer via modulation doping at Ge sites

Aiming at improving the thermoelectric (TE) performance of the GeTe monolayer by means of doping, we systematically investigate the TE properties of the doped GeTe monolayers. By testing most of the atoms in Groups IIA-VA, we found that Be, Mg, Sn, and Pb are possible dopants in view of their stability and electrical conductivity. It is shown that the doping atom types and the doping concentrations can make different influences on the electronic energy band structures, the phononic spectra, and the electronic (phononic) transmission spectra. Furthermore, the Seebeck coefficientS, the electrical conductanceG, the power factorS2G, and the electronic (phononic) thermal conductancesκe(ph)will be changed to varying extents. Finally, we find that the resulting figures of meritZTs are closely dependent on the doping atom types and the doping concentration. In comparison with the pristine GeTe monolayer, theZTpeaks of the doped one can be manipulated by the atomic doping. At appropriate doping concentrations for different doping atoms, theseZTpeaks can be improved. Our findings demonstrate the feasibility of using Be, Mg, Sn, and Pb as the dopants to enhance the TE performance of the GeTe monolayer.