Graphene formation by electron beam induced deposition

C. SILVA; F. BONETTO; S. MONTORO; A. CANDIA; M. PASSEGGI; R. VIDAL

San Luis

Encuentro; VIII Encuentro de Física y Química de Superficies; 2018

In this work, we analyze the carbonaceous films grown on Cu(111) by means of electron beam induceddeposition (EBID) using ethylene as precursor gas.The study was performed for two different precursor gas pressures in an UHV chamber, and twosubstrate temperatures. In the whole set of experiments, we started with a clean Cu(111) sample andthe other parameters involved in the process such as the energy and current density of the electronswere kept constant.To characterize the films during the formation process we used AES (Auger Electron Spectroscopy) andEELS (Electron Energy Loss Spectroscopy). These techniques allow us to determine the relative amountof carbon deposited on the surface, and to establish the type of carbon atoms bonds at the surface. Wefound that there is no influence of the substrate temperature on the amount of carbon deposited at lowexposures. However, at high ethylene exposures, the amount of carbon deposited decreases if thesubstrate temperature increases. An analysis of the CKLL line shape of the final Auger spectra measuredafter each deposition demonstrates that the chemical structure of the surface carbon compounds is thesame for all the samples grown by EBID.The rate of carbon deposition is constant for the first 4000 L, regardless of ethylene pressure (P) andsubstrate temperature (T). Above this level of exposure, some dependence with P and T is observed.Both, AES and EELS spectra indicate a majority of sp2bonds in the carbon structures formed on thesurface, consistent with the formation of a graphitic compound (or graphene).Scanning tunneling microscopy (STM) and Raman spectroscopy were used as complementary, butdecisive, techniques to assess the structured of the obtained films. From all the results obtained we canconclude that the carbonaceous films are formed by patches of defective few layer (1-2) graphene.