Channel Material For Field-effect Transistors Research Articles

Nonvolatile Switching in Graphene Field-Effect Devices

The absence of a band gap in graphene restricts its straightforward application as a channel material in field-effect transistors. In this letter, we report on a new approach to engineer a band gap in graphene field-effect devices (FEDs) by controlled structural modification of the graphene channel itself. The conductance in the FEDs is switched between a conductive ldquoon-staterdquo and an insulating ldquooff-staterdquo with more than six orders of magnitude difference in conductance. Above a critical value of an electric field applied to the FED gate under certain environmental conditions, a chemical modification takes place to form insulating graphene derivatives. The effect can be reversed by electrical fields of opposite polarity or short current pulses to recover the initial state. These reversible switches could potentially be applied to nonvolatile memories and novel neuromorphic processing concepts.

Analysis of graphene nanoribbons as a channel material for field-effect transistors

Electronic properties of graphene (carbon) nanoribbons are studied and compared to those of carbon nanotubes. The nanoribbons are found to have qualitatively similar electron band structure which depends on chirality but with a significantly narrower band gap. The low- and high-field mobilities of the nanoribbons are evaluated and found to be higher than those of carbon nanotubes for the same unit cell but lower at matched band gap or carrier concentration. Due to the inverse relationship between mobility and band gap, it is concluded that graphene nanoribbons operated as field-effect transistors must have band gaps <0.5eV to achieve mobilities significantly higher than those of silicon and thus may be better suited for low power applications.