Quantum capacitance in scaled down III–V FETs

We have built a physical gate capacitance model for III–V FETs that incorporates quantum capacitance and centroid capacitance in the channel. We verified its validity with simulations (Nextnano) and experimental measurements on High Electron Mobility Transistors (HEMTs) with InAs and InGaAs channels down to 30 nm in gate length. Our model confirms that in the operational range of these devices, the quantum capacitance significantly lowers the overall gate capacitance. In addition, the channel centroid capacitance is also found to have a significant impact on gate capacitance. Our model provides a number of suggestions for capacitance scaling in future III–V FETs.