INVESTIGATION OF THE THRESHOLD VOLTAGE OF MOSFETS WITH POSITION-DEPENDENT AND POTENTIAL-DEPENDENT INTERFACE TRAP DISTRIBUTIONS USING A FIXED-POINT ITERATION METHOD

Simulation results are presented for a MOSFET with position and energy (potential) dependent interface trap distributions which may be typical for devices subjected to interface trap producing processes such as hot-electron degradation. The interface trap distribution is modeled as a Gaussian peak at a given position along the channel while the energy dependence is derived from C-V measurements from an MOS capacitor exposed to ionizing radiation. A novel fixed-point technique is used to solve the two-dimensional boundary-value problem. The technique is shown to be globally convergent for arbitrary distributions of interface traps. A comparison of the convergence properties of the Newton and fixed-point methods is presented, and it is shown that for some important cases the Newton technique fails to converge while the fixed-point technique converges with a geometric convergence rate. © 1990 IEEE