Transient simulation of semiconductor devices using the Monte-Carlo method

A technique to extract transient currents from Monte-Carlo (MC) simulation data is described. It is based on the fact that the integrated terminal current obtained from the MC data is a reasonably smooth function of time and can be easily fitted with a polynomial. The transient current is obtained by simply differentiating the polynomial. The technique is an effective way to get around the statistical noise problem that is inherent in the MC method. A MESFET structure is discussed as an example and the transient terminal currents due to a step change in the gate voltage are obtained. The current gain h₂₁ of the MESFET is computed from the transient currents. The technique described here can be trivially extended to other semiconductor devices and it can be a very useful tool in estimating microwave performance, large-signal behavior, switching response in logic circuits etc.