Transport spectroscopy in single-electron tunneling transistors

摘要

Tunneling through quantum dots is determined by the interplay between charging effects and the discrete energy-level spectrum originating from the three-dimensional confinement. We have performed spectroscopic measurements of many-particle ground and excited states in a single quantum dot by studying the linear and nonlinear transport. The occupation of excited states can lead to the appearance of negative differential conductance and to a suppression of transport via the ground states of the system. In a double-quantum-dot system consisting of two quantum dots of different sizes the measured conductance through the system is influenced by the charging energies of the individual dots and the coupling between the two dots.