Si quantum dots (QDs) individually charged with a few electrons or holes show characteristic potential profiles with a dimple around the center of the dot which can be interpreted in terms of Coulomb repulsion among the charges retained in the dot. By an introduction of Ge core in Si dots, holes can be well-confined in the Ge core while electrons are stored in the Si clad because of the energy band discontinuity at the interface between the Si clad and the Ge core. The influence of ionized impurity doping to Si-QDs on their electron charging and discharging characteristics has also been studied. For metal-oxide-semiconductor (MOS) capacitors and n-channel MOS field-effect-transistors (n-MOSFETs) with Si-QDs floating gates, distinct multiple-step charging to and discharging from the Si-QDs floating gate have been confirmed at room temperature, which are regulated presumably by redistribution of injected electrons in the Si-QDs floating gate for further electron injection and emission. (c) 2008 Elsevier B.V. All rights reserved.