An effect occurring in a p-n junction under forward bias. In a semiconductor with a relatively long bulk lifetime, excess minority carriers injected across the junction remain near the junction as a net concentration of charge. When reverse bias is applied to the junction the effect of the carriers stored near the junction is to produce a reverse current across the junction substantially greater than the normal reverse saturation current; this current flows until all the stored charges have been removed either by recombination or by crossing back across the junction under the influence of the reverse bias. The time interval between application of the reverse bias and cessation of the reverse current surge is the storage time of the junction.

When several diodes are used together in a rectifier circuit that also contains inductive elements, the carrier storage can result in undesirable transients in the circuit and limits the frequency at which such circuits can be operated. The storage effect is however utilized in the step-recovery diode.