Modeling the pH response of silicon nitride ISFET devices

Simulations using the site binding theory were carried out considering both the response of buried sites and the surface oxidation of silicon nitride. These non-ideal effects were modelled using simplified functions that infl uence the site densities of the silicon nitride. The simulations were compa red with measurements on electrolyte-insulator-silicon (EIS) structures. Th e results obtained did show good correspondence between simulations and mea surements. Buried sites were found to increase the sensitivity of ISFET dev ices, in contrary to surface oxidation which causes a decrease of the sensi tivity. The time between pH change and measurements has proved to be the mo st significant factor determining non-linearity and hysteresis of the senso r signal and sensitivity. (C) 2000 Elsevier Science S.A. All rights reserve d.