This paper presents a brief overview of the physics of nanosilicon materials for single-electron device applications. We study how a nanosilicon grain and a discrete grain boundary work as a charging island and a tunnel barrier by using a point-contact transistor, which features an extremely short and narrow channel. Single-electron charging phenomena are investigated by comparing as-prepared devices and various oxidized devices. The optimization of grain and grain-boundary structural parameters is discussed for improving the Coulomb blockade characteristics and realizing room temperature device operation. (C) 2003 Published by Elsevier B.V.