Finite size effects on the gate leakage current in graphene nanoribbon field-effect transistors

The finite size effects in nanoribbon graphene field-effect transistors (FETs) make the energy distribution of the channel electrons very different from that when neglecting finite size effects. Such an effect is especially obvious when the width of the graphene ribbon is a few nanometers. Thus, it results in more high-energy electrons in a nanoribbon graphene FET than in a two-dimensional graphene FET for the same device structure and parameters. Furthermore, such an energy distribution of channel electrons results in a change in the gate leakage current of a nanoribbon graphene FET. The numerical calculations demonstrate that the tunneling current rapidly increases with decreasing width of the graphene ribbon. This implies that a workable graphene FET after considering gate oxide reliability should have a channel width larger than 100 nm.