XPS Studies of the SiO₂ Substrates and Thermoelectric Thin Films of Sn/Sn+SnO₂ under the Effects of the Different Thermal Treatments

Abstract

Multilayered thermoelectric Sn/Sn+SnO2 thin films were prepared using KJL DC/RF magnetron sputtering system under Ar gas plasma on the SiO₂ substrates. The thicknesses of the fabricated thin films were found using Filmetrics UV thickness measurement system. The fabricated thin films were annealed at different temperatures for one hour to tailor the thermoelectric properties. In this study, unannealed, annealed at 150 and 300°C samples were characterized using Thermo Fisher XPS system brought to the Alabama A&M University by the NSF-MRI support. X-ray Photoelectron Spectroscopy (XPS), also known as Electron Spectroscopy for Chemical Analysis (ESCA) is a type of analysis used for characterization of various surface materials. XPS is mostly known for the characterization of thin films-which are coatings that have been deposited onto a substrate and may be comprised of many different materials to alter or enhance the substrate’s performance. XPS analysis provides information for composition, chemical states, depth profile, imaging and thickness of thin film. This paper focuses on the application of XPS techniques in thin film research for Sn/Sn+SnO₂ multilayered thermoelectric system and SiO₂ substrates annealed at different temperatures. Since SiO₂ substrates were used during the deposition of the multilayer thin films, we would like to perform detailed XPS studies on the SiO₂ substrates. SiO₂ substrates is being used with many researchers, this manuscript will be good reference for the researchers using SiO₂ substrates. Thermal treatment of the substrates and the multilayered thin films has caused some changes of the XPS characterization including binding energy, depth profile, peak value and FWHM. The treatment effects were discussed and compared to each other.