We investigated the device performance of graphene nanoribbon tunneling field-effect transistors with heterogeneous channel as a function of the contact doping concentrations. The simulations were carried out based on the non-equilibrium Green's function, coupled with a Dirac Hamiltonian model, and the roles of symmetric and asymmetric contact doping concentrations on the device performance were identified. It was observed that the device performances such as OFF-state currents (I-OFF). ON-state currents (I-ON) and subthreshold slopes (SSs) were greatly influenced by the source doping concentrations, while variations in drain doping concentrations changed mainly the I-OFF. By applying proper asymmetric source and drain doping concentrations, low SS and large I-ON/I-OFF ratio can be achieved, indicating that it is an alternative route to effectively enhance the device performance. (c) 2012 Elsevier Ltd. All rights reserved.