Numerical techniques have been used to obtain the potential and electron concentration distribution and the resultant drain current in a Buried Channel MOS transistor in its subthreshold region.
The exponential dependence of the drain current on the gate-to-source bias voltage has been observed in the subthreshold region where the current conduction mechanism is distinctly different from that in the linear region.
The experimental measurement of the drain current shows a good agreement with the result of the numerical calculation despite the many approximations and assumptions involved in modelling the device.