Simulation of graphene base transistors with bilayer tunnel oxide barrier: Model calibration and performance projection

A simulation study of the graphene base transistor is presented based on the most recent experimental results involving a novel double-layer emitter-to-base insulator made of TmSiO and TiO2. The simulations are based on a 1-D quantum transport model with the effective mass approximation, and reproduce well the experiments both in terms of current levels and common-base current gain $\alpha $ . Performance projections are then investigated: with transparent graphene, the cutoff frequency is predicted to increase from 1 to 100 MHz by reducing the thickness of TmSiO from 1 to 0.5 nm. In order to go beyond this limit toward the terahertz range, a material with a lower barrier height than TmSiO should be considered. A technological breakthrough boosting the graphene interface quality is also needed in order to obtain acceptable values of $\alpha $ , which are still low.