Compact model for long-channel cylindrical surrounding-gate MOSFETs valid from low to high doping concentrations

This paper presents a compact model for the electrostatic potentials and the current characteristics of doped long-channel cylindrical surrounding-gate (SRG) MOSFETs. An analytical expression of the potentials is derived as a function of doping concentration. Then, the mobile charge density is calculated using the analytical expressions of the surface potential at the surface and the difference of potentials between the surface and the center of the silicon doped layer. Using the expression obtained for the mobile charge, a drain current expression is derived. Comparisons of the modeled expressions with the simulated characteristics obtained from the 3D ATLAS device simulator for the transfer characteristics, as well for the output characteristics, show good agreement within the practical range of gate and drain voltages and for doping concentrations ranging from 1016 cm−3 to 5 × 1018 cm−3.