How to discharge the pn junction capacitance
It self-discharges in much less than a second usually.

Ir at Vr rises with many factors usually power rating. Similarity Cr rises with Pd rating but may drop with high Vr ratings for diodes and rises in Schottky diodes over Silicon diodes.

Consider: https://www.fairchildsemi.com/datasheets/FJ/FJH1100.pdf

"Ultra low,leakage signal diode"

It is 2pF at Vr = 0V and Ir is 3pA at Vr=5V.

We expect C at Vr=5V to be much less , let's say &lt;1pF.  thus Rr=5V/3pA and C&lt;1pF so RC=T &lt; 5/3 seconds



Now let's look at the body diode in a 500A IGBT.

http://www.pwrx.com/pwrx/docs/cm450dx-24s1_e.pdf. (see note 1)


then see Qrr = 12 μC (typ.) at 3.4V from turnon to off 
then see Ices= 1 mA (max)at Vce=Vces=1000V with Vgs=O


since C=Q/V and Rces=Vces/Ices=1MΩ 
but C(1000V) will be about &lt;1% of C(3.4V) {roughly} and thus  RcesCs&lt;1M12μ*1%*C/1kV=12ks which seems wrong