Nonequilibrium green function technique for analyzing electron transport through single and two levels of interacting quantum dot

Abstract

The electron transport through nanoelectronic device, fabricated by coupling a QD into two metallic electrodes, is analyzed theoretically using Non-equilibrium Green function formalism. The considered QD has one quantum level with one-site coulomb interaction (two-channel for transportation). The spectra function of this QD is obtained by using Feynman diagram technique for single-level model and the equation of motion method for two-level model. Analytical approximations of electric current through this device are presented at low temperature and at finite temperature. Depending on the analytical approaches, we will analyze the dependency of nano-device current on the QD size, level width, and temperature. Finally, the dependency of current on the applied voltages is analyzed with respect to coulomb-blocked diamonds. The current-applied voltages characteristics help us to understand the behavior of nano-devices that has two channels of transport. We will show where and why the two-channel nano-device shows two and one current steps depending on the chosen value of gate voltage.