XPS monitoring of SrVO3 thin films from demixing to air ageing: The asset of treatment in water

International audienceIn this work, 40 nm-thick films of SrVO3 (SVO) grown by Pulsed Laser Deposition (PLD) on SrTiO3 substrates are studied by X-Ray Photoelectron Spectroscopy (XPS). We develop here a systematic fitting procedure for both Sr3d, V2p3/2 and O1s spectral regions of interest associated to the different chemical environments. Joint angle resolved XPS and Ar ion depth profiling reveal that as-grown SVO thin films exhibits Sr-rich phases at the extreme surface and a near-stoichiometric SVO in the bulk. The removal of segregated Sr is proposed by a treatment in deionized ultrapure water. This step will become an essential technological step in order to obtain reproducible surfaces achieving a stoichiometric SVO oxide phase. Besides, these hydrolyzed SVO surfaces appears VO2 terminated and then more electrically active. Furthermore, an air-ageing comparative study between as-grown and H2O-treated samples reveals that hydrolyzed surfaces are more surface sensitive to air oxidation. Such observations will be crucial and must be carefully considered before performing any passivation process for the integration of SVO thin film into next generation electronics heterostructures