Morphology and Magneto-Transport in Exfoliated Graphene on Ultrathin Crystalline ?-Si3N4(0001)/Si(111)

This work reports the first experimental study of graphene transferred on?-Si3N4(0001)/Si(111). A comprehensive quantitative understanding of thephysics of ultrathin Si3N4 as a gate dielectric for graphene-based devices isprovided. The Si3N4 film is grown on Si(111) under ultra-high vacuum (UHV)conditions and investigated by scanning tunneling microscopy (STM). Subsequently,a graphene flake is deposited on top of it by a polymer-based transfertechnique, and a Hall bar device is fabricated from the graphene flake. STMis employed again to study the graphene flake under UHV conditions afterdevice fabrication and shows that the surface quality is preserved. Electricaltransport measurements, carried out at low temperature in magnetic field,reveal back gate modulation of carrier density in the graphene channeland show the occurrence of weak localization. Under these experimentalconditions, no leakage current between back gate and graphene channel isdetected.