Strain effect on the electronic and optical properties of Germanene/MoS2 heterobilayer

The strain effect on the electronic and optical properties of Germanene/MoS2 heterobilayer have been investigated by using first principles calculations with vdW corrections. Different stacking patterns of Germanene/MoS2 heterobilayer have been designed, which all show similar electronic and optical properties. Germanene is found to interact with MoS2 monolayer via weak vdW interactions, only leading to a tiny band gap opened with its Dirac cone well preserved. This implies MoS2 monolayer can be a suitable semiconducting substrate for germanene adhension. Through various in-plane external strains, the opened Dirac gap of heterobilayer can be further modulated and a semiconductor-metal transition even occurs. In addition, the Germanene/MoS2 heterobilayer can exhibit much wider optical adsorption range together with a red-shift in adsorption edge compared to individual layers. The position and intensity of optical adsorption peaks in ultraviolet and visible light regions also can be effectively tuned by applying external strains. With the strain controllable electronic and optical properties, Gemanene/MoS2 heterobilayer is expected to be a candidate for applications in new functional nanoelectronic and optoelectronic devices.