Modeling the CMOS Characteristics of a Completely Depleted Surrounding-Gate Nanotransistor and an Unevenly Doped Working Region

Abstract

The issues of modeling the basic electrophysical characteristics of fully depleted surrounding-gate CMOS nanotransistors with an unevenly doped working region are discussed. The case of a Gaussian impurity distribution in the radial direction with the maximum in the center of the working area is analyzed. A mathematical model of the potential distribution following from an analytical solution of the 2D Poisson equation is treated. The results of model calculations of the potential distribution of a sub-50 nm structures are in good agreement with the data obtained using the commercially available ATLAS^TM software package for the 2D modeling of transistor structures. Based on the obtained potential distributions, the characteristics of the current are calculated using the tested approach formulated in the charge separation concept. For the topological norms chosen, optimization of the steepness of the doping profile provides an additional opportunity to control the key characteristics, together with the radius of the working region and the thickness of the gate oxide. This is important when analyzing the applicability of the analyzed nanotransistor structures.