Thermoelectric properties of gated graphene ribbons in the ballistic regime

We investigate the thermoelectric properties of gated graphene ribbons in the ballistic transport limit using linear response theory and the Landauer formalism. The dependence of the electronic conductance, thermopower as well as electronic thermal conductance on both Fermi level and temperature are clarified and the validity of Wiedemann-Franz law is examined. The electronic part of thermoelectric figure of merit ZTelZTel which gives an upper bound for the thermoelectric efficiency of the gated ribbons, is also calculated. It is shown that ZTelZTel of wide and short gated ribbons is directly related to geometric aspect ratio of the graphene ribbon and for very short ribbons can exceed unity at room temperature. Our results could be useful in the design of efficient graphene-based thermoelectric devices.

► We investigated the thermoelectric properties of gated graphene ribbons.
► We clarified both the temperature and Fermi level dependence.
► Our results are consistent with recent thermoelectric measurements.
► We calculated the electronic part of the thermoelectric figure of merit ZTel of gated ribbons.
► For wide and short ribbons the electronic ZTel can exceed unity at room temperature.