TUNNEL MESOSCOPIC STRUCTURE UNDER PULSE ELECTROMAGNETIC-FIELD

We consider resonant tunneling through metal-insulator-metal tunnel ju nctions via impurity centres in the barrier region when the electron s tate at tile impurity centre has a nonzero mean dipole moment. If a pu lse electromagnetic (EM) field of an external laser source is applied to the structure, it adds a series of photon replicas to the impurity level, which results in the formation of resonant peaks in the total t ransmission probability. The relative strengths of the peaks depend on tile statistical properties of the EM radiation. We propose a new met hod of creating the condition for resonant tunneling in such a structu re, when one of the photon replicas fits the impurity level into reson ance. If the laser pulse has a rectangular envelope of duration tau th e tunneling current related with a photon replica increases at times t less than or equal to tau as [1 - exp(-Gamma t)] (here 1/Gamma is the tunnel escape rate from the impurity centre). The current is maximum at t = tau. This fact gives the possibility to estimate the pulse dura tion from the electric current measurements in our scheme. Hence, me p ropose the structure under consideration as a possible tool for direct ly measuring the tunnel properties of the structure, the laser pulse d uration, and for detecting the statistical properties of the EM radiat ion.