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-sem iconductor field-effect transistor (MOSFET) equipped with a gate on three s ides 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. T he observed temperature dependence of the peak height and the presence of a n intrinsic line width imply the participation of a constant number of ener gy levels in the zero-dimensional transport. At the same time, the peak spa cing varies strongly from peak to peak, which is further evidence of quantu m-mechanical transport through zero-dimensional states.