  We study impact of the near-interfacial oxide traps on the C-V and I-V
characteristics of graphene gated structures. Methods of extraction of
interface trap level density in graphene field effect devices from the
capacitance-voltage measurements are described and discussed. It has been found
that the effects of electron-electron or hole-hole interactions and
electron-hole puddles can be mixed in C-V characteristics putting obstacles in
the way of uniquely determined extraction of the interface trap density in
graphene. Influence of the interface traps on DC and AC capacitance and
conductance characteristics of graphene field-effect structures is described.
It has been shown that variety of widths of resistivity peaks in various
samples could be explained by different interface trap capacitance values.
