Non-GCA Modeling of Near Threshold IV Characteristics of DG MOSFETs
- Author(s): Ren, Zhongjie
- Advisor(s): Taur, Yuan
- et al.
It is well known that the velocity saturation behavior is not negligible in the shorter channel length and the gradual channel approximation (GCA) fails to generate reasonable I-V characterisitics of MOSFETs for both n = 1 and n = 2 models. Therefore, the non-GCA model has been developed to solve this issue by adding the ∆Q (Source-Drain induced part for mobile charges) term which is absent in the conventional GCA models and exhibits an excellent performance for above threshold region (Vgs-Vt>0.27V) modeling. However, the near threshold modeling (Vgs-Vt<0.1V) is not ideal in the previous non-GCA model
with linear Qi(V) when compared with TCAD simulations owing to the failure of matching the Qi(V) (Gate induced part for mobile charges) profile in that region. In this work, a more rigerous non-GCA model with piecewise Qi(V) which can successfully approach I-V behaviors of DG MOSFETs in the near threshold region for n = 1 and n = 2 has been proposed by extending the continous, analytical GCA model of Qi(V) to obtain negative values. In addition, relative favorable above threshold I-V characteristics can be calculated by utilizing the proposed non-GCA model as well.