Calculated I-V characteristics of low-dimensional structures

In this work we calculate the I-V characteristics of quantum dot devices. The I-V curves of such structures are dependent not only upon the dot spectrum, but also on whether they are connected to bulk contacts or to contacts confined in one or more direction. Here we concentrate on 1D-0D-1D and 3D-0D-3D devices, using two different techniques: a transfer-matrix approach and a non-equilibrium Green's function formalism. The Coulomb interaction and single particle aspects are included in the theory. For 1D-0D-1D structures the I-V curve consists of a series of upward and downward steps, the latter being present only if the Coulomb repulsion inside the dot is important. These downward steps prove to be thermally robust. For 3D-0D-3D devices the I-V curve is dominated by peaks rather than steps, reflecting the difference in density of states in the contacts. Comparison with experiments shows very good agreement.