A two-dimensional semi-analytical analysis of the subthreshold-swing behavior including free carriers and interfacial traps effects for nanoscale double-gate MOSFETs

In the present paper, an accurate surface potential and the subthreshold swing (S) models including the free carriers and interfacial traps effect have been presented. Exploiting these new device models, we have found that the incorporation of the free carriers' effect leads to the improvement of the subthreshold swing accuracy in comparison with the classical models. The inclusion of the free carriers has a major role in determining the subthreshold parameters behavior due to the extra surface potential generated at the interface, which may affect the electric field and carriers transport in weak inversion regime. We have demonstrated that S is very sensitive to the short channel lengths (L less than 40 nm). For a device with a small silicon body thickness (tsi=5 nm), S is increased dramatically with the reduction of the channel length. The developed approaches are verified and validated by the good agreement found with the 2D numerical simulations for a wide range of device parameters and bias conditions. The proposed models can also be implemented into devices simulators, such as SPICE, to study the degradation of nanoscale digital CMOS-based circuits.