Analysis of subthreshold swing in junctionless cylindrical surrounding gate MOSFET using Gaussian doping profile

The subthreshold swing (SS) model is presented for a junctionless cylindrical surrounding gate (JLCSG) metal oxide semiconductor field effect transistor (MOSFET) with a Gaussian doping profile. Since the Poisson's equation using the Gaussian doping profile has no closed form solution in cylindrical coordinate, the potential distribution is obtained using the Taylor series expansion of the error function and exponential function. The SS model presented in this study is considered to be reasonable, comparing the SSs of 3D simulation and other papers. As a result, the smaller the projected range Rp and straggle〖 σ〗_p , the smaller the SS. However, when the projected range is 1/2 of the silicon radius R, the SS remains constant regardless of the change of the straggle. The SS increases when straggle increases in RpR/2. Therefore, the SS should be kept low by adjusting the projected range and straggle in JLCSG MOSFET with gaussian doping profile.