Effect of the tunneling rates on the conductance characteristics of single-electron transistors

We present calculations of the linear-response conductance of a SiGe based single-electron transistor (SET). The conductance and the discrete charging of the quantum dot are calculated by free-energy minimization. The free-en ergy calculation takes the discrete level-spectrum as well as complex many- body interactions into account. The tunneling rates for tunneling through t he source and lead barrier are calculated using Bardeen's transfer Hamilton ian formalism [1]. The tunneling matrix elements are calculated for transit ions between the zero-dimensional states in the quantum dot and the lowest subband in the one-dimensional constriction. We compare the results for the conductance peaks with those from calculations with a constant tunneling r ate where the shape of the peaks is only due to energetic arguments.