WOx phase growth on SiO2/Si by decomposition of tungsten hexacarbonyl: Influence of potassium on supported tungsten oxide phases

摘要: Synchrotron based photoemission spectroscopy was used to study the adsorption of tungsten hexacarbonyl on SiO2 surfaces modified by potassium. Results were compared with ones obtained when no potassium present. Experiments using W4f and Si2p intensities variations show that, at 140 K, growth proceeds via a simultaneous multilayer mode for two kinds but differences in compositions growing layers. Indeed, it is evidenced even cryogenic temperatures, presence induces decomposition significant part molecules through strong interaction between atoms opposition potassium-free surface cases where W(CO)6 are simply physisorbed. Additional irradiation adsorbed photons coming from 0-order synchrotron radiation, subsequent going back room temperature additional thermal treatments up about 700 K then induce further precursor. It allows as well get rid carbon and, finally, stabilize different W-based species surface. The state remaining strongly influenced When present, highly oxidized observed, whereas reduced mainly detected surfaces. Moreover, diffusion revealed during formation phase, one should guess that plays crucial role oxidation mechanism.