N ov 1 99 7 Resonant Tunneling Spectroscopy of Interacting Localised States – Observation Of The Correlated Current Through Two Impurities

We study effects of Coulomb interactions between localised states in a potential barrier by measuring resonant-tunneling spectra with a small bias applied along the barrier. In the ohmic regime the conductance of 0.2µm–gate lateral GaAs microstructures shows distinct peaks associated with individual localised states. However, when an electric field is applied new states start contributing to the current, which becomes a correlated electron flow through two interacting localised states. Several situations of such correlations have been observed, and the conclusions are confirmed by calculations.