Transmission through graphene of electrons in the 30 – 900 eV range
Alice Apponi, Domenica Convertino, Neeraj Mishra, Camilla Coletti, M. Iodice, F. Frasconi, F. Pilo, Narcis Silviu Blaj, Daniele Paoloni, Ilaria Rago, Giovanni De Bellis, G. Cavoto, A. Ruocco
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.