4.6 Transient Behavior

A reason for the lack of experimental evidence for the effect could be that it has a large time constant. In this case possible transient measurement techniques which sweep the applied voltage would not capture the effect. Fig. 4.17 shows the body potential as function of time obtained by a transient simulation using the standard energy transport model.

Figure 4.17: Body potential of the SOI (Device 1) obtained by a transient energy transport simulation.

Due to the very small current produced by the injected electrons, the decrease of the body potential is quite slow. The drain current obtained for different ramp-functions for the drain voltage $V_{DS}$ can be seen in Fig. 4.18. The sweep-time in this figures ranges from $100 \, \mathrm{ns}$ to $100 \, \mathrm{ms}$.

Figure 4.18: Drain currents of the SOI (Device 1) obtained by a transient energy transport simulation showing different sweep times.

In Fig. 4.19 the time-dependence of the body potential is shown with the sweep time as parameter. First the body potential increases because of the capacitive coupling to the drain. Then the parasitic DC current due to hot carrier diffusion begins to dominate over the displacement current and charges the body negatively.

Figure 4.19: Body potentials of the SOI (Device 1) obtained by a transient energy transport simulation showing different sweep times.

From Fig. 4.18 and Fig. 4.19 it can be seen that a possible transient measurement of the effect has to use a moderately long sweep-time.

M. Gritsch: Numerical Modeling of Silicon-on-Insulator MOSFETs PDF