Separation-dependent electronic transparency of monolayer graphene membranes on III-V semiconductor substrates.

Ultrahigh vacuum scanning tunneling microscopy and first-principles calculations have been carried out to study monolayer graphene nanomembranes deposited in situ onto UHV-cleaved GaAs(110) and InAs(110) surfaces. A bias-dependent semitransparency effect is observed in which the substrate atomic structure is clearly visible through the graphene monolayer. Statistical data analysis and density functional theory calculations suggest that this semitransparency phenomenon is due to the scanning tunneling microscope tip pushing the graphene membrane away from its equilibrium location and closer to the substrate surface, causing their electronic states to intermix.