Device models and simulation of high-low doping transition regions and their effects on N-MOSFET circuits

Parametric models for high-low doping transition algorithms and their DC, AC and transient responses in solid state integrated circuit devices are developed. The model performance characteristics are compared with device-level simulations using MINIMOS 5.2 software. These results show significant discrepancy in equivalent circuit parameters, as compared to that of the intrinsic part of MOSFETs. The discrepancy is more significant for thin film depletion type n-MOSFETs operating in the subthreshold region. The transient and dynamic performance of a depletion type n-channel MOSFET, a device with two high-low doing transition regions, is studied. The analysis predicts a diffusion capacitance of 3.4 pF/μm², and a depletion capacitance of 0.2 pF/μm² across the high-low transition. The current contribution of the stored charge to the switching response is investigated