Abstract
A new approach to treating the problem of the frequency response of tunneling barriers is demonstrated. The Schrödinger equation for an incident monoenergetic electron is solved in the case of a double-barrier structure with an applied potential oscillating at an arbitrary frequency. The details of the tunneling in the transient stage and the following steady state, as well as the charging and discharging processes around the structure, are revealed in the high-frequency modulation regime. We find that the linear frequency response for a typical fast structure rolls off above 1.5 THz with a 1/f dependence. An enhancement in the nonlinear frequency response at 770 GHz is observed for a single electron tunneling. From the motion of the wave front in the structure, we find that the phase transit time across the structure ranges from 140 to 40 fs decreasing with frequency. Generation of the transmitted pulses with an energy spread about ℏω where ω is the angular modulation frequency is observed. This corresponds to an emission and absorption of a quantum of ℏω.