Surviving Process Variation: Investigation of CNR MOSFETs With Tapered Channels Using Fully Self-Consistent NEGF and Tight-Binding Methods

A fully self-consistent 3-D device simulator which combines nonequilibrium Green´s function and atomistic tight-binding Hamiltonian for carrier transport is developed to characterize the performance of double-gate carbon nanoribbon (CNR) MOSFETs. Our simulation indicates a strong dependence of device performance on ribbon width and a conventional dependence on channel length. A novel tapered-channel geometry is proposed to counter these effects caused by inevitable process variation. An intuitive explanation is provided for this design approach, followed by detailed numerical simulation results. It is concluded that quantum-based atomistic device simulators provide both - characteristics and internal physical properties of CNR MOSFETs, thus playing a critical role in the design and optimization of nanoscale devices.