CHARACTERIZATION OF TIO2 SIO2 MULTILAYERS BY HIGH-RESOLUTION TRANSMISSION ELECTRON-MICROSCOPY AND ELECTRON-ENERGY-LOSS SPECTROSCOPY/

Titanium dioxide and silicon dioxide multilayer stacks with typical th icknesses of a few nanometres have been evaporated by two electron bea m guns. The high resolution transmission electron microscopy (HRTEM) a nd electron energy loss spectroscopy (EELS) techniques were used to ch aracterize the microstructure and chemical composition of these multil ayer stacks. The HRTEM images show that the SiO2 layers are amorphous as expected, while the TiO2 layers present traces of crystallinity eve n for small thicknesses. The EELS analysis of the recorded Si L(23), O K and Ti L(23) edges reveals that the O K edge in TiO2 exhibits a pre peak due to the presence of unoccupied O 2p-Ti 3d hybridized states, w hich constitutes another clear identification of the TiO2 layers.