X-ray photoemission spectroscopy study of the surface chemistry of laser-assisted chemical vapour deposition SnO_x thin films after exposure to hydrogen

In this paper we present the results of X-ray Photoemission Spectroscopy (XPS) study of the surface chemistry of Laser-assisted Chemical Vapour Deposition (L-CVD) deposited tin oxide SnO_x thin films before and after subsequent exposure to molecular hydrogen (hydro- genation) at room and elevated temperature up to 800 K. As-deposited L-CVD tin oxide thin films exhibited a nonstoichiometric composition with a relative concentration [0]/[Sn] equal to 1.29±0.05. After exposure to 10⁵ L of hydrogen at room temperature the relative concentration [O]/[Sn] was almost the same. After the same exposure to hydrogen at elevated temperature the relative concentration [O/Sn] decreases what confirms the effect of drastic reduction to the almost stoichiometric tin oxide SnO thin films. This evident reduction of L- CVD tin oxide thin films was confirmed by the shape analysis of corresponding XPS Sn3d_5/2 and OIs peaks using the deconvolution procedure in which the different contribution of O- Sn²⁺ and 0-Sn⁴⁺ bond ings were determined.