Tunable band gaps and high carrier mobilities in germanene by Si doping in the presence of an external electric field: Field effect transistors

We have systematically investigated the electronic properties of Si doping germanene under external electric fields by the first-principle calculations. The results show that a wide range of linearly tunable and sizable direct band gaps for the Ge31Si1 and Ge28Si4 systems (3–1048 meV and 6–716 meV) are merely determined by the strength of the electric field. More importantly, the high carrier mobilities of the stable Ge31Si1 and Ge28Si4 systems are largely retained under external electric field. The mechanism of charge transfer confirms the p-type semiconductor properties in the Si doping germanene systems. These results indicate that the electronic properties of Si doping germanene can be effectively modulated under the external electric field, providing a potential application in novel electronic devices, such as Field effect transistors.