Zero-dimensional states in a quantum dot, formed at threshold in a disordered submicron silicon transistor

Single-electron tunnelling is studied in a narrow submicron metal-oxide-semiconductor field-effect transistor (MOSFET) equipped with a gate on three sides of the channel. Coulomb oscillations are observed below 20 K, while a much broader structure persists up to 50 K. Every conductance peak is found to decrease with temperature, corresponding to a single-level resonance. The observed temperature dependence of the peak height and the presence of an intrinsic line width imply the participation of a constant number of energy levels in the zero-dimensional transport. At the same time, the peak spacing varies strongly from peak to peak, which is further evidence of quantum-mechanical transport through zero-dimensional states.