I have used reverse recovery method for measurement of carrier lifetime. I have used a simple setup consisting of a function generator, a resistance and DUT
(design under test). In a conventional transient response, there is a constant current phase and a recovery phase and effective carrier lifetime can be determined from
these equations in this link.
But transient response which I have measured, has not constant current phase and after switching, begins decaying to reverse saturation current.
My question is, why there is not constant current phase in transient response? Is it related to If/Ir ratio? Is there any consideration about If/Ir ratio in reverse recovery method? Thank you.