Transmission through graphene of electrons in the 30 – 900 eV range

Abstract

Here, we report on accurate transmission measurements of electrons below 1 keV through suspended monolayer graphene. Monolayer graphene was grown via chemical vapor deposition and transferred onto transmission electron microscopy (TEM) grids. A monochromatic electron gun has been employed to perform the measurements in the 30 – 900 eV range in ultra-high vacuum. The graphene transparency is obtained from the absolute measurement of the direct beam current and the transmitted one, by means of a Faraday cup. We observed a transmission going from ∼20 to ∼80% for monolayer graphene within the experimental electron energy range. The high quality and the grid coverage of the suspended graphene has been proved via micro-Raman, X-ray photoemission, electron energy loss spectroscopies and field-emission scanning electron microscopy. After a 550 °C in-vacuum annealing of the samples, the main contribution to the C 1s spectrum is due to the sp2 component and the evidence of suspended monolayer graphene has been observed through the π-plasmon excitation.