Tuning the electronic structure of rhombohedral and cubic GeTe for thermoelectric application: Influence of molybdenum doping

Abstract

Substitutional doping to engineer the electronic structure of materials has received high prominence in developing high performance thermoelectric materials. Herein, we study the effect of molybdenum doping on the electronic structure of GeTe and provide insights into the observed enhancement of thermoelectric performance. We discover that Mo doping has a huge impact on the band structure of both rhombohedral and cubic phase of GeTe. In addition to increasing the band gap, Mo doping causes huge increase in the density of states near the Fermi level. We also notice convergence of valence sub-bands and hyperconvergence of conduction sub-bands besides introduction of multiple carrier valleys promoting transport in both p and n-type materials. These features undoubtedly make Mo doping a beneficial approach in the development of lead free GeTe thermoelectrics.