Optimization of quantum capacitance and improvement of RF performance in dual-ribbon GNRFET by tuning the GNR-to-GNR distance

Abstract

We have optimized the RF parameters in dual-ribbon GNRFET transistors by reducing the GNR-to-GNR distance. We used the semi-empirical computational method of extended Hückel theory for calculations. The total capacitance arises from the combination of a parallel-plate electrostatic capacitance and quantum capacitance, wherein the second factor dominates in the overall calculation. To compute the quantum capacitance, we employed the density of states integral. Simulation results confirm the presence of non-uniform behavior in the C–V characteristic curve. Transmission conductance, intrinsic gate delay, power delay product, and \({f}_{\text{T}}{L}_{\text{g}}\) product are evaluated in this study. The results indicate that the RF performance of the dual-ribbon device can be significantly improved by reducing the GNR-to-GNR distance. Decreasing the GNR-to-GNR distance by 2 nm (from 2.5 to 0.5 nm) improved the \({f}_{\text{T}}{L}_{\text{g}}\) product by 510% for GNR (6,0) and increased it approximately 20-fold for GNR (7,0). That dimensional change reduced the intrinsic gate delay by 83.6% for GNR (6,0) and 90% for GNR (7,0). Additionally, a 13.6-fold reduction in PDP for GNR (6,0) and an 11-fold reduction in GNR (7,0) are other results of reducing GNR-to-GNR distance.