▎ 摘　　要

We propose an analytical device model for a graphene nanoribbon field-effect transistor (GNR-FET) under the dc and ac operating conditions. The GNR-FET under consideration is based on a heterostructure, which consists of an array of nanoribbons clad between the highly conducting substrate (the back gate) and the top gate controlling the dc and ac source-drain currents. Using the model developed, we derive explicit analytical formulas for the GNR-FET transconductance as a function of the signal frequency, collision frequency of electrons, and the top gate length. The transition from the ballistic to strongly collisional electron transport is considered. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3029715]