Evidence of Mixed Oxide Formation on the Cu/SiO2 Interface

5 years ago

Evidence of Mixed Oxide Formation on the Cu/SiO2 Interface

Marcos Flores, Noelia Benito

The deposition of Cu onto SiO₂ has been carried out by electron beam evaporation in order to study the interface formation by X-ray photoelectron spectroscopy and angle resolved X-ray photoelectron spectroscopy. Shifts in the binding energy of Cu 2p_3/2 and Si 2p bands, as well as in the Cu LMM kinetic energy, have been observed during the growth. These changes are indicative of a modification in the coordination number of Cu or the formation of M–O–M′ cross-linking bonds at the interface. Moreover, different coordination states of Cu⁺ and Cu²⁺ (tetrahedral and octahedral) have been detected. Apart from different coordination numbers, a new chemical state appears during the Cu/SiO₂ interface formation. This new contribution, Cu^x+, is attributed to the formation of a mixed oxide Cu-O-Si. Additionally, two different stages of growth of the Cu/SiO₂ interface have been observed: The first one, where no metallic Cu is detected and a mixture of copper oxides is measured onto the SiO₂ substrate, and the second one, in which metallic Cu appears on the surface and a multilayer Cu⁰/Cu^x+/Cu oxides/SiO₂ can be inferred.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b06563

DOI: 10.1021/acs.jpcc.7b06563