Nonlinear transport through an ensemble of quantum dots

We apply a master equation approach to model vertical electron tunneling through a large array of self-organized quantum dots. We take into account the electrostatic coupling of carriers in different dots. For an inhomogeneous system of quantum dots the calculated current-voltage characteristic shows strong nonlinear effects such as negative differential conductance. Particularly, in the case of strong fluctuations of the coupling rates to the collector a precursor peak can occur. Additionally, fluctuations of the energy levels in different dots can generate an anomalous temperature behavior of the current similar to that observed in recent experiments. (C) 2002 Elsevier Science B.V. All rights reserved.