Vertical currents due to interatomic Coulombic decay in experiments with two coupled quantum wells

Interatomic Coulombic decay (ICD) is an ionization phenomena that takes place due to the Coulombic electronic repulsion force that correlates the ionized electrons with the other electrons. Here we present an analytical analysis of the ICD in two coupled quantum wells (QWs) which shows that the ICD ionization of an electron is in the perpendicular direction to the semiconductor layers. This happens when two conditions are satisfied. The first condition requires the excitation of the two electrons from the valence band. The first electron is excited to the bottom of the excited subband in one quantum well, and the second to the bottom of the first subband of the adjacent QW. The second condition ensures that the distance between the wells is large enough. In our case the two QWs are far apart when the distance between the two QWs is larger than 80 Å. Only vertical currents are expected in such a case. These conditions can be verified by future experiments.