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 thicknesses of a few nanometres have been evaporated by two electron beam guns. The high resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) techniques were used to characterize the microstructure and chemical composition of these multilayer stacks. The HRTEM images show that the SiO2 layers are amorphous as expected, while the TiO2 layers present traces of crystallinity even 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 prepeak due to the presence of unoccupied O 2p-Ti 3d hybridized states, which constitutes another clear identification of the TiO2 layers.