【Epitaxy Papers】Investigation of SiO₂:HfO₂ Composition Effects on ALD HfSiOₓ as Gate Dielectric on β-Ga₂O₃ (001)

      Researchers from the University of Michigan have published a dissertation titled " Investigation of SiO₂:HfO₂ Composition Effects on ALD HfSiOₓ as Gate Dielectric on β-Ga₂O₃ (001)" in IEEE Transactions on Electron Devices.

Abstract

      This study investigated the dielectric properties of HfSiO_x thin films deposited on β-Ga₂O₃, with a focus on the effects of SiO₂:HfO₂ composition ratio and post-deposition annealing (PDA) environment using deep ultraviolet (DUV)-assisted capacitance–voltage (C–V) and current–voltage (I–V) measurements. Initial results showed no clear trend between composition and performance, attributed to HfSiO_x/Ga₂O₃ interfacial layer formation. To minimize interfacial layer effects, a thicker initial SiO₂ layer was introduced, enabling a clear correlation between composition ratio and dielectric behavior. Transmission electron microscopy (TEM) and corresponding energy-dispersive X-ray spectroscopy (EDS) further confirmed a well-defined interface between the dielectric and the Ga₂O₃ substrate. Oxygen PDA improved dielectric constant (~10.6), and significantly reduced interface trap density (~6.1 × 10¹² cm⁻² eV⁻¹) compared to air annealing (~11.9 × 10¹²  cm⁻² eV⁻¹).

DOI：

https://doi.org/10.1109/TED.2026.3670802