NUMERICAL AND CHARGE SHEET MODELS FOR THIN-FILM SOI MOSFETS

Numerical and charge sheet models applicable for all bias conditions are presented for the channel currents of long-channel SOI MOSFET’s. From a comparison of the two models it is shown that the charge sheet analytic model accurately predicts the channel currents from weak to strong inversion regions. The results include analytic expressions for the drift and diffusion current components of individual channel currents, front-gate and back-gate interaction parameter as well as an analytic correlation between the surface potentials of the front and back channels when there is coupling between the two gates under nonthermal equilibrium conditions. The effect of SOI film thickness on the drain current is investigated under different bias conditions of the back gate and it is shown that thin films are beneficial from the point of increased drain currents if the back channel is in depletion or inversion. It is also shown that, in addition to the charge coupling effects, dynamic interaction between the channels exists if the static current in one of the channels saturates. © 1990 IEEE