MSE Masters Thesis Presentation: Zaiyang Zhang

MSE Master’s Thesis Final Presentation: Zaiyang Zhang

TITLE: Pulsed Laser Deposition and Characterization of Indium Oxide Thin Films on Native-Oxide-Covered Silicon (111) Substrates

ADVISOR: Kevin Smith, Physics, MSE

COMMITTEE: Karl Ludwig, MSE

ABSTRACT: Indium oxide (In₂O₃) is a transparent conducting oxide with unique electronic properties, including an intrinsic surface electron accumulation layer (SEAL). Despite extensive study on lattice-matched substrates, systematic characterization of pulsed-laser-deposited In₂O₃ on native-oxide-covered Si(111) remains limited. This thesis investigates In₂O₃ thin films grown by pulsed laser deposition (PLD) on as-received Si(111) substrates retaining a ~1–2 nm native oxide interlayer, using a KrF excimer laser (248 nm) at 1.61 J/cm², ~550 °C substrate temperature, and 0.074 mbar oxygen pressure. Two depositions of 6000 and 8000 laser shots were characterized by X-ray photoelectron spectroscopy (XPS), with the 8000-shot film additionally examined by X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), and atomic force microscopy (AFM). XPS revealed uniform surface composition (~51% In, 41% O, 8% C) and a modest increase in In³⁺–O lattice bonding fraction from ~43.0% to ~47.7% with higher shot count. XRD confirmed the cubic bixbyite phase with an elevated I(400)/I(222) ratio (~1.6 vs. 0.35 powder reference), indicating preferential orientation, and Scherrer-derived crystallite sizes of ~23–38 nm. SEM showed continuous film coverage, while AFM yielded RMS roughness values of 0.34–1.58 nm across 1–30 µm scan sizes. The results demonstrate that PLD is a viable route for growing crystalline In₂O₃ directly on native-oxide-covered Si(111), producing films with confirmed bixbyite structure, sub-nanometer smoothness, and consistent stoichiometry..