Exact modeling of the transient response of an MOS capacitor

Abstract

The dynamic properties of a metal-oxide-semiconductor capacitor are simulated using numerical techniques. Time-dependent behavior of the electrons and holes is obtained for large-signal transient applications in the presence of deep-lying Shockley-Read-Hall (SRH) recombination centers. The computation is performed throughout the entire device including both the insulator and semiconductor materials. Self-consistent implicit numerical algorithms were developed to solve simultaneously the exact time-dependent continuity equations for electrons and holes, Poisson's equation for the electrostatic potential and the rate equations for both donor- and acceptor-type SRH centers. Stable solutions are obtained for the transient response from flatband to strong inversion which ranges over many decades of time. The results include the simulation of the transient response of a thin substrate MOS capacitor from flatband to inversion. The computer results are explained and compared to the existing theories of transient MOS capacitance. Wherever possible, comparisons of computed results are made for the cases with and without the inclusion of SRH recombination centers. The main results point out the deficiencies in the existing interpretation of the Zerbst plot and offer alternative explanations.