1. Give a simple reason based on device physics or charge store concept to show that the speed up of the recovery during switch-off transient is given by the ratio, JF/JR. Afterwards, show this also mathematically using the solutions given in the text.
2. Obtain the switching transient solutions for a thin-base diode with the p+/n/m structure where n is the thin base of geometrical thickness XB and XBB. n/m is a perfect ohmic contact of infinite recombination rate. Use the charge control model and assume minority carrier diffusion dominant. The mathematics is very simple.