An explicit surface potential model of bulk-MOSFETs with inclusion of poly-gate accumulation, depletion, and inversion effects

An explicit surface potential model of the bulk-MOSFET with inclusion of the poly-gate accumulation, depletion, and inversion effects is derived from the basic MOS device physics and its solution result is also discussed in this paper. By the means of the appropriate approximations and device physics derivation, the complex group of the surface-potential and poly-silicon potential equations is transformed into one single explicit surface potential equation of a MOSFET with the poly-silicon accumulation/depletion/inversion effects. It is demonstrated that the proposed surface potential equation and its solution correctly yet accurately describe the physical behaviors of the poly-silicon potential, surface potential, gate charge, the gate capacitance, with continuous and smooth transitions from the accumulation region, thorough the depletion region, finally to the strong inversion region. The predicted MOSFET trans-capacitance behavior is verified by the result of fully numerical iteration method, thus, the surface potential equation presented can be used in advanced surface potential based MOSFET compact model development.