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.
