Electron microscopy and Rutherford backscattering study of nucleation and growth in nanosized W-Ti-O thin films

Structural characterization of nanosized W-Ti-O rf magnetron-sputtered films was carried out by means of electron microscopy techniques and Rutherford backscattering spectroscopy. The evolution of the W-Ti-O films turned out to be quite complex as several nanophases were determined. Depending on annealing temperature and W/Ti abundance, stable nanophases of WO3, TiO, and TiO2 have been reliably achieved. The investigation highlighted the reason why the films remained nanostructured in spite of a relatively high annealing temperature. In fact, formation of a dispersed TiO nanophase in the W-Ti-O layers was recognized to inhibit grain growth and promote secondary recrystallization. This resulted in exaggerated growth of WO3 crystallites over the nanostructured layers. (C) 2000 American Institute of Physics. [S0021-8979(00)08514-5].