Modeling of ion drift in 4H-SiC-based chemical MOSFET sensors

The effect of mobile ions on electrical performance in ion-sensitive metal-oxide-semiconductor field effect transistor fabricated on 4H silicon carbide for the application as chemical fluid and gas sensors in harsh environments was investigated. The drift and diffusion of these mobile ions in the dielectric gate stack were identified as the source for a change in the sensor signal. The movement of the ions and the resulting electrical properties were successfully modeled using a novel drift-diffusion model implemented in TCAD simulation software. The diffusion coefficient and activation energy for drift and diffusion of sodium through an amorphous silicon nitride layer were estimated from these simulations.