What is the reverse recovery time of semiconductor diode?

When a diode passes from forward biased to reverse biased it takes a short period of time for the charge carriers in the vicinity of the junction to recombine and create a nonconducting depletion region. During this time period the diode conducts in the reverse direction, this is called the reverse recovery time.

Its different for every kind of diode, to get the value for a specific diode consult the datasheet.