Quantum confinement effect in self-assembled, nanometer silicon dots

The first subband energy at the valence band of self-assembled silicon quan tum dots grown by low-pressure chemical vapor deposition on ultrathin SiO2/ Si substrates has been measured as an energy shift at the top of the valenc e band density of states by using high-resolution x-ray photoelectron spect roscopy. The systematic shift of the valence band maximum towards higher bi nding energy with decreasing the dot size is shown to be consistent with th eoretical prediction. The charging effects of the silicon dots and the SiO2 layer by photoelectron emission during the measurements have been taken in to account in determining the valence-band-edge energy. (C) 1998 American I nstitute of Physics. [S0003-6951(98)02052-X].