  Graphene devices require electric contacts with metals, particularly with
gold. Scanning tunneling spectroscopy studies of electron local density of
states performed on mono-, bi- and tri- graphene layer deposited on metallic
conductive Au/Cr/SiO2/Si substrate shows that gold substrate causes the Fermi
level shift downwards which means that holes are donated by metal substrate to
graphene which becomes p-type doped. These experimental results are in good
accordance with recently published density function theory calculations. The
estimated positions of the Dirac point show that the higher number of graphene
layers the lower Fermi level shift is observed.
