Effect of the crystalline constitution of TiO2 substrates on the growth of ultrathin Mo layer

Abstract Metallic molybdenum was deposited by magnetron sputtering on amorphous and (110) rutile TiO 2 substrates. An interfacial reaction between the deposited Mo and the TiO 2 substrates generating Ti 3 + , Ti 2 + oxidation states is evidenced by X-ray photoelectron spectroscopy. Our XPS data suggest, as compared to the (110) rutile substrate, a higher reactivity of the amorphous TiO 2 leading to a stronger Mo oxidation. In both cases, this reaction, leads to the formation of MoO x nanostructures at the interfaces. The growth mechanism of the Mo deposit as a function of the crystalline constitution of the TiO 2 substrate was analyzed by processing the XPS data using the Quases ® software. The data reveal a layer-by-layer growth of the Mo deposit on the (110) rutile substrate and a Stranski–Krastanov growth on the amorphous one. We explain these different growth modes based on the TiO 2 surface reactivity and electronic structure using the Cabrera–Mott theory. This explanation is supported by Time-of-Flight Secondary Ion Mass spectrometry profiling.