Ion Beam Assisted Deposition of Biaxially-Textured Thin Films for Energy Applications

Ion beam assisted deposition (IBAD) is a promising way to realize high efficient and scalable manufacturing of a single-crystal-like, biaxially-textured thin film on various substrates. This biaxially-textured film has been employed for different kinds of purposes, such as epitaxial growth of single-crystal-like high-temperature superconductor (HTS) films and replacing the wafer-based epitaxial process for thinfilm optoelectronic and electrical applications such as flexible solar cells and thin-film transistors. This dissertation is focused on different IBAD processes that could benefit both the semiconductor and superconductor fields. A highly biaxially-textured IBAD TiN was demonstrated on the Hastelloy tape without foreign oxide seed layers. This enables the feasibility of all-electrically conductive buffers on Hastelloy. The conventional architecture of LaMnO3/IBAD MgO for HTS tapes was also improved through the use of Ag/TiN intermediate layers. The buffer architecture was optimized to achieve significant improvement in texture and avoid possible crystalline defects. The texture of LaMnO3 was improved to (002) Δω of 1.7⁰ and (110) Δϕ of 2.45⁰ using Ag/TiN layers. Additionally, IBAD MgO and related HTS cap layers have been developed on flexible non-metallic tape. The non-metallic substrate could extend the scope of HTS materials to unconventional applications such as high-quality flexible MRI receiving coils and transmission lines for cryogenic quantum computing systems. Finally, a novel architecture of single-crystalline-like ultra-bandgap semiconductor β-Ga2O3 film on IBAD MgO-capped flexible Hastelloy was demonstrated. The β-Ga2O3 film shows a strong biaxial texture with (400) Δω of 1.54⁰ and {002} Δϕ of 4.81⁰. The crystal orientation relationship between the β-Ga2O3 and IBAD MgO was also studied.