Explicit continuous charge-based compact model of surrounding gate MOSFET (SRGMOSFET) with smooth transition between partially-depleted to fully-depleted operation

Abstract

A charge-based compact model that includes the dynamic depletion behavior for arbitrary doped surrounding gate MOSFET (SRGMOSFET) is presented in this paper. The one-dimensional Poisson's equation is first solved to obtain the continuous explicit solution of the mobile charge density and drain current expression. A smooth transition between partially-depleted (PD) and fully-depleted (FD) regions of the channel potential is then obtained by using perturbation approach in deriving its corrected surface potential due to the ionized dopant carrier. This corrected surface potential is used to calculate the bulk charge and subsequently captured the dynamic depletion behavior of the surface potential. The comparison between the analytical model and 2D TCAD simulation demonstrates good agreement not only for a wide range of terminal biases, dopant concentration and geometry sizes, but also captured the characteristics of SRGMOSFET such as volume inversion and smooth transition between PD and FD regions. The surface potential agreed well with numerical TCAD simulation results for dopant-geometry ratio (  qN R 4 A 2 Si ) of approximately 0.9, which is about 50% improvement of accuracy compared to the FD compact models of only at 0.45.