Quantum confinement energy in nanocrystalline silicon dots from high-frequency conductance measurement

Electron charging and discharging processes in floating gate metal–oxide–semiconductor memory based on nanocrystalline silicon (nc-Si) dots were investigated at room temperature using capacitance–voltage and conductance–voltage (G–V) measurements. From charged nc-Si dots, a sequential electron discharging processes was clearly observed in G–V spectroscopy. The fine structure in the observed conductance peaks has been interpreted in terms of the Coulomb blockade and quantum confinement effects of nc-Si dots, which allowed the electron-addition energy to be estimated at 50 meV. Taking the electron-charging energy between the silicon substrate and the floating dot (30 meV) into account, the quantum confinement energy was found to be as significant as the electron charging energy for nc-Si dots, with ∼8 nm in diameter, embedded in silicon oxide.