Coulomb correlation effects in tunneling processes through localized impurity states

Petr I. Arseyev^1,* and Natalia S. Maslova²

Non-equilibrium Coulomb effects in resonant tunneling through deep impurity states are analyzed. It is shown that corrections to the tunneling vertex caused by the Coulomb potential result in a nontrivial behavior of tunneling characteristics and should be taken into account. One encounters effects similar to the Mahan edge singularities in the problem of X - ray absorption spectra in metals. The Coulomb vertex corrections lead to a smoothed power law singularity in current-voltage characteristics. The effect is well pronounced if tunneling rate from a deep impurity level to metallic tip is much larger than relaxation rate of non-equilibrium electron density at the localized state. This condition can be satisfied in experiments with a deep impurity state in the semiconductor gap.

PACS: 73.40.Gk