Modeling of subthreshold characteristics of non-planar multi-gate inGaAs quantum well field effect transistor

Abstract

In this work, a physically based analytical model for the threshold voltage and subthreshold swing of non-planar trigate InGaAs quantum well field effect transistor (QWFET) has been developed. The model is derived from the analytical solution of the 3D Poisson’s equation including the electron concentrations. Based on the subthreshold electrostatic potential obtained from the solution of the Poisson’s equation, the threshold voltage and the subthreshold swing are obtained by considering the changes at the top of the barrier at the leakiest channel path. The results from the proposed model are compared to the results from numerical simulator (NEGF mode-space solver) for a wide range of gate length and lateral dimensions of the channel; hence good agreement between the analytical model and the numerical model is observed. Applying the developed model, the sensitivities of threshold voltage and subthreshold swing to channel length, fin height, fin width and donor layer thickness are investigated. The subthreshold characteristics of the planar single-gate and double-gate QWFET devices are also modeled; and they are compared to the non-planar trigate QWFET in terms of performance. The non-planar structure is found to provide better subthreshold swing and stronger enhancement mode operation than its planar counterpart. Short-channel effects of the trigate QWFET can be reasonably controlled by reducing either the fin height or fin width. The aggressively scaled non-planar trigate QWFET proves to be the better option for short channel operation.