Resonant tunneling and a nonlinear response in RF fields

The problem of resonant tunneling through a double-barrier nanostructure in a strong alternating electric field is solved completely. To this end, a perturbation method is proposed. Electron wavefunctions and a nonlinear response are obtained in analytical form over wide ranges of field frequencies and amplitudes, using the perturbation method and the semiclassical approximation. The semiclassical expression for the current allows for contributions of all orders with respect to the field, i.e., electron transitions with the emission and absorption of any number of photons. This enables one to find the limits of resonant current and output power. The case of ℏω≫Γ is considered, where ℏ is the rationalized Planck constant, ω is the field frequency, and Γ is the resonance level width. It is established that the maximum resonant current is approximately as high as half the resonant constant current. For the quantum regime of oscillation, the output power can be 106–107 W/cm2 at ω=1013 s−1 and the output power rises with ω, in contrast to the well-known classical regime, where the power decreases rapidly.