Evolution of the chemical composition of Sn thin films heated during x-ray photoelectron spectroscopy

•Surface composed of particulate regions of Sn oxide encapsulated metallic Sn core.•Annealing leads to reduction of SnO2 to SnO and slight increase of Sn.•Annealing above 350 °C leads to reduction of Sn and increase in Si and its oxides.•Particulate regions increased in size to 21 nm and are well separated at 450 °C.