ac conductance of single-electron resonant-tunneling systems

Resonant tunneling under ac bias through a semiconducting quantum dot is investigated. In the case of a single resonant level in the dot, we take into account the Coulomb repulsion between electrons with opposite spins. Using the irreducible Green’s-function method, the propagator of the electrons in the well is obtained for the case of zero dc bias. The equation for the average number of electrons in the potential well is solved self-consistently and the density of states for the electrons in the well is obtained for typical parameter values. The conductance and the energy losses of the two-barrier system are calculated in the linear-response formalism. The conductance curve exhibits a resonantlike behavior when the external frequency Ω equals the Coulomb repulsion energy ${\mathit{E}}_{\mathit{c}}$. Likewise, the energy-loss curve has a pronounced minimum at this frequency.