Magnetron sputtering deposition of Mg<sub><italic>x</italic></sub>Ge<sub>1–</sub><sub><italic>x</italic></sub>Te thermoelectric thin films
Abstract
<p indent="0mm">Thermoelectric materials with high thermoelectric figures of merit are essential for the application of thermoelectric devices. Therefore, the synthesis research of high thermoelectric figure of merit materials can play a pivotal role in solving energy problems in the future. In the middle temperature region <sc>(300–800 K),</sc> GeTe-based alloy materials are considered thermoelectric materials with advanced properties. Alternative doping methods, including substitution or interstitial doping, have been extensively investigated with regards to bulk materials. On this basis, we used advanced magnetron sputtering technology to prepare alternatively doped Mg/GeTe thermoelectric films with different concentrations and analyzed their thermoelectric properties. The results revealed that the Mg atoms in the GeTe lattice can change the effective carrier mass. The Seebeck effect and, consequently, the power factor increase with increasing mass. Mg<sub>0.04</sub>Ge<sub>0.96</sub>Te reached a maximum of 53.4 μW cm<sup>–1</sup> K<sup>–2</sup> at <sc>710 K.</sc> In addition, regarding the thermal transport mechanism, we believe that Mg is substituted for doping in GeTe. The introduction of disordered phases in the film can inc rease phonon scattering, leading to a significant decrease in thermal conductivity. Moreover, the optimization process yields a very small thermal conductivity (3.10 W m<sup>–1</sup> K<sup>–1</sup>) for Mg<sub>0.1</sub>Ge<sub>0.9</sub>Te. In conclusion, Mg<sub><italic>x</italic></sub>Ge<sub>1−</sub><sub><italic>x</italic></sub>Te is an excellent p-type semiconductor thermoelectric material with a maximum thermoelectric merit of 1.02. The results are valuable for basic research and development of new nontoxic and high-performance thermoelectric materials.</p>
