TRANSPORT SPECTROSCOPY ON A SINGLE QUANTUM-DOT

Lateral transport through a quantum dot defined by the split-gate technique in a two-dimensional electron gas is investigated as a function of backgate voltage and emitter-collector bias voltage. This measurement technique allows us to identify the regimes of single-electron tunnelling. Within these regimes, excited states of the electron system in the quantum dot provide additional transport channels which can be classified as being opened in resonance with the Fermi level of either the emitter or the collector. The method of transport spectroscopy is discussed. When performing spectroscopy in a magnetic field, one has to take into account that the magnetic field affects not only the electronic states of the quantum dot but also the electronic states in the electrodes surrounding the quantum dot.