The energy band alignment of Si nanocrystals in SiO(2)

The determination of the energy band alignment between the 2.6-nm-diameter Si nanocrystals and the SiO(2) host is achieved by means of photo-ionization/-neutralization and capacitance spectroscopy. The measured conduction and valence band offsets are 2.6 eV and 4.4 eV. The band gap is evaluated to be 1.7 eV by photoluminescence. These results indicate that the valence band offset at the Si nanocrystals/SiO(2) interface is quite close to the one observed at bulk Si/SiO(2) interface. On the contrary, we observe a clear upward shift (0.5 eV) of the conduction band in the Si nanocrystals/SiO(2) system with respect to the bulk Si/SiO(2) hetero-structure.