Experimental Study of Barium Strontium Titanate High-K Gate Dielectric on Beta Gallium Oxide Semiconductor
Date of Award
M.S. in Electrical and Computer Engineering
Department of Electrical and Computer Engineering
Development of high permittivity, or high-κ dielectrics for ultra-wide bandgap (UWBG) materials, such as β-Ga₂O₃, is critical to the electric field management in devices made with UWBG semiconductor materials . Typically, high-κ dielectrics are deposited using high-temperature processes, such as pulsed laser deposition (PLD), which poses a significant challenge in the development of β-Ga₂O₃ devices. This thesis is focused on studying the quality of high-κ dielectric BaₓSr₁₋ₓTiO₃ (BST) deposited using PLD on ALD-grown SiO₂ on Sn-doped (010) β-Ga₂O₃ substrates. The PLD deposition parameters of thickness, target composition, and deposition temperature were varied to study multiple variations of BaₓSr₁₋ₓTiO₃ MOSCAP devices. BST deposition conditions were identified to produce a device with an effective breakdown field Eeff,BD ≥ 30 MV/cm within the BST/SiO₂ dielectric stack with a current leakage ≤ 10⁻⁸ A/cm² at Eeff< 5.8-7.6 MV/cm. Interface defect density was analyzed for these devices using the conductance method  and photo-assisted capacitance-voltage (C-V) measurements . The devices with the largest Eeff,BD showed a shallow-level defect density Dit ≤ 10¹² cm⁻²-eV⁻¹ and deep-level defect density Nit ~ 2x10¹² cm⁻². The extracted shallow and deep-level interface defect densities indicated a high defect density at the dielectric/semiconductor interface, affirming the need for further interface optimization. This work demonstrates successful fabrication of a BST on β-Ga₂O₃ MOSCAP device, offering supporting motivation for further investigation into the use of high-κ BST for β-Ga₂O₃ devices.
Electrical Engineering, Engineering, Materials Science, Nanotechnology, dielectrics, gallium oxide, MOSCAPs, characterization, BST, Barium Strontium Titanate
Copyright © 2023, author
Miesle, Adam Thomas, "Experimental Study of Barium Strontium Titanate High-K Gate Dielectric on Beta Gallium Oxide Semiconductor" (2023). Graduate Theses and Dissertations. 7221.