  The integration of high-k oxide on graphene using atomic layer deposition
requires an electrically reliable buffer layer. In this study, Y was selected
as the buffer layer due to the highest oxidation ability in rare earth elements
and various oxidation methods (atmospheric, high-pressure O2 and ozone) were
applied to the Y metal buffer layer. By optimizing oxidation conditions of the
top gate insulator, we successfully improve the capacitance of top gate Y2O3
insulator and demonstrate a large Ion/Ioff ratio for bilayer graphene under an
external electric field.
