The basic contribution to
arises from the interaction of the channel charge and
the gate metal. Additionally, fringe capacitances [13] are added due to coupling between
the semiconductor caps, the ohmic metal, and the gate metal. The capacitance
is therefore
written as:

The additional term is added to point out the effect of the generation/recombination of additional carriers when applying a third terminal voltage. The difference between RF- and DC- due to the activation of traps and carrier generation/recombination in a dynamic process with time constants of the order of s is generally acknowledged [211]. Above frequencies of excitation of a few MHz (see Chapter 6) this results in a stable, time invariant equilibrium which is extracted in RF-measurements [196]. Above a few MHz it is further independent of the frequency, yet, not of the applied bias. It is very desirable to reduce the effects of generation/recombination. The inclusion of these effects into device modeling [248] is helpful to explain the dependence of device properties on bias. The bias dependence of is further strongly related to the shape and the carrier charge concentration distribution of the space charge region. The compact model assumes a charge at an effective distance

2001-12-21