Direct Growth of Germanene at Interfaces between van der Waals Materials and Ag(111)

Abstract

Germanene, a graphene-like honeycomb crystal of germanium, has been attracting immense attention owing to its exotic properties such as a tunable bandgap and high carrier mobility. However, the fabrication of germanene-based electronic devices is difficult owing to its chemical instability. To overcome this problem, we proposed and developed a new method of germanene growth at graphene/Ag(111) and hexagonal boron nitride/Ag(111) interfaces. The grown germanene at the interfaces was stable in air and uniform over the entire area covered with a van der Waals (vdW) material. As an important finding, a vdW interface provides a nanoscale platform for growing germanene similarly to that in vacuum, while this cannot be achieved with a typical oxide interface (Al₂O₃). We believe that our work is of significantly importance not only for the growth of germanene but also for the fabrication of future germanene-based electronic devices.