Electroic and optical properties of germanene/MoS 2 heterobilayers: first principles study

First principles calculations have been performed to investigate the structural, electronic, and optical properties of germanene/MoS 2 heterostructures. The results show that a weak van der Waals coupling between germanene and MoS 2 layers can lead to a considerable band-gap opening (53 meV) as well as the preserved Dirac cone with a linear band dispersion of germanene. The applied external electric filed can not only enhance the interaction strength between two layers, but also linearly control the charge transfer between germanene and MoS 2 layers, and consequently lead to a tunable band gap. Furthermore, the reduction in the optical absorption intensity of the heterostructures with respect to the separated monolayers has been predicted. These findings suggest that the Ge/MoS 2 hybrid can be designed as the device where both finite band gap and high carrier mobility are required.