  We propose to measure Purcell effect by observing the current through a
semeiconductor quantum dot embedded in a microcavity. An electron and a hole
are injected separately into the quantum structure to form an exciton and then
recombine radiatively. The stationary current is shown to be altered if one
varies the cavity length or the exciton energy gap. Therefore, the Purcell
effect can be observed experimentally by measuring the current through the
quantum structure. In addition, we also find superradiance of excitons between
quantum dots may also be observed in an electrical way.
