Peculiarities in XPS spectra of Sn/SiO2 layers as an effect of surface charge

• Published in: Results in physics 2024-06, Vol.61, p.107733, Article 107733
• Main Authors: Liu, Poting, Freiberg, Katharina, Grinter, David C., Sivakov, Vladimir
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition; Composite; Oxygen exchange; Surface charging; Synchrotron; Tin; X-ray photoelectron spectroscopy
• ISSN: 2211-3797; 2211-3797
• DOI: 10.1016/j.rinp.2024.107733

•Effective oxygen exchange between silicon and tin oxide phases occurs during the growth of tin oxide layer on the Si surface.•The localized surface charge has a significant effect on the obtained XPS core level spectra.•Large Sn particles coupled to the Si wafer are not charged compared to the smaller tin nanoparticles localized in the matrix. X-ray photoelectron spectroscopy based on synchrotron radiation was used to investigate the composition of the observed SnO2-x/Sn:SiO2-x thin layer grown by organometallic chemical vapour deposition on single-crystalline silicon wafer with additional argon ions etching treatment. Due to the formation of a thermodynamic anomaly during in situ layer growth, an efficient oxygen exchange between silicon and tin oxide phases occurs. The present study addresses the effect of localized surface charging and its influence on the obtained XPS core level spectra. We found that due to the high electrical conductivity of metallic tin and the direct coupling of tin particles to the silicon wafer, the XPS Sn 3d5/2 core level spectrum is not affected by the surface charge compared to the highly charged dielectric silicon oxide matrix, as observed for the XPS O 1 s and Si 2p core level spectra. Our results show that the core level spectra of Si 2p and O 1 s are shifted up to 3 eV due to the presence of uncompensated positive charge on the surface of the silica matrix. These results provide insight into the influence of surface charge effects on the analysis of conductor/insulator composite materials and contribute to the application of Sn-based materials in various application concepts related to energy and surface functionalization.