Tunable electronic properties in the van der Waals heterostructure of germanene/germanane.

It is challenging to epitaxially grow germanene on conventional semiconductor substrates. Based on first-principles calculations, we investigate the structural and electronic properties of germanene/germanane heterostructures (HTSs). The results indicate that the Dirac cone with nearly linear band dispersion of germanene is maintained in the band gap of the substrate. Remarkably, the band gaps opened in these HTSs can be effectively modulated by the external electric field and strain, and they also feature very low effective masses and high carrier mobilities. These results provide a route to design high-performance FETs operating at room temperature in nanodevices.