FREQUENCY-DEPENDENT CONDUCTANCE OF TUNNEL-JUNCTIONS

The a.c. conductance of a quasi-one-dimensional system with a potentia l barrier is calculated in linear response. Its frequency dependence i s used to define a dynamic capacitance. The influence of phase-breakin g electron-phonon interactions is investigated. It is argued that Coul omb interaction is of minor importance at higher frequencies. The low- frequency limit for the suppression of Coulomb interaction is estimate d for GaAs-AlGaAs point contacts. The relation between the dynamic and the static capacitance is discussed.