forward conduction

Also, following the end of forward conduction in any diode, there is reverse current for a short time.

The diode must immediately enter into forward conduction mode as the driving current is interrupted.

When diodes switch from forward conduction to reverse cut-off, a reverse current flows briefly as stored charge is removed.

By injecting minority carriers (holes) from the collector p+ region into the n- drift region during forward conduction, the resistance of the n- drift region is considerably reduced.

The main phenomenon used in SRDs is the storage of electric charge during forward conduction, which is present in all semiconductor junction diodes and is due to finite lifetime of minority carriers in semiconductors.

This reduces the overall capacitance and the capacitance range by half, but possesses the advantage of reducing the ac component of voltage across each device and symmetrical distortion should the ac component possess enough amplitude to bias the varicaps into forward conduction.

The Turn-OFF switching transient of silicon-based power bipolar semiconductor devices, caused by stored charge in the device during the forward conduction state, limits switching speed of the device, which in turn limits the efficiency of the application it is used within.

As the blocking voltage rating of both MOSFET and IGBT devices increases, the depth of the n- drift region must increase and the doping must decrease, resulting in roughly square relationship decrease in forward conduction vs. blocking voltage capability of the device.

Now suppose that the voltage bias abruptly changes, switching from its stationary positive value to a higher magnitude constant negative value: then, since a certain amount of charge has been stored during forward conduction, diode resistance is still low (i.e. the anode-to-cathode voltage V has nearly the same forward conduction value).