Ex-Situ Ellipsometry of Doped Gallium Oxide Thin Films Abstract

Atomic Layer Deposition (ALD) is a self-limiting, precise chemical vapor deposition technique used to build semiconductors. This process involves depositing two or more precursors onto a Silicon or Saphire wafer preceding surface layer reactions, creating a thin monolayer film from the reactants. These films are used in many modern technologies, from hydrogen fuel cells to photovoltaic solar cells to gas sensing technology. This research used ex-situ ellipsometry to characterize doped and undoped gallium (III) oxide's (Ga2O3) thickness and refractive index. Films were randomly chosen for ex-situ annealing at 650℃. From this ex-situ ellipsometry, we could see that the recipe affected the thickness, with the Silicon doped being smaller, around 46.607 nm, and the Tin doped being larger, around 65.207 nm. The undoped or lightly doped films were between 54.408 nm and 56.695 nm. The change in recipe had no change in the refractive index. Annealing of the films changed both the refractive index and the thickness of the film, with annealed films having a smaller refractive index and a larger average thickness. Our results allow us to better characterize gallium (III) oxide films, doped and undoped, printed from Atomic Layer Deposition, and apply them to modern technologies.