Optical Absorption of the Nanostructured SiO₂ in Ultraviolet-Near Infrared Light Range

The electronic structure of nanostructured SiO₂ was studied by means of ultravioletnear infrared absorption spectra. A strong and broad absorption band was observed in the wavelength range of ultraviolet-near infrared light. This band is caused by the electronic transition from the valence band to the defect energy level in the bandgap which was theoretically calculated by using molecular orbital approach. With increasing the annealing temperature, the red shift of this band was observed. The mechanism of this band is discussed.