【Epitaxy Papers】Epitaxial growth and characterization of hexagonal ε-(InₓGa₁₋ₓ)₂O₃ (x=0.05 and 0.15) on AlN

      Researchers from the Texas State University have published a dissertation titled "Epitaxial growth and characterization of hexagonal ε-(InₓGa₁₋ₓ)₂O₃ (x=0.05 and 0.15) on AlN" in Journal of Physics D: Applied Physics.

Abstract

      The growth parameter optimization to deposit the hexagonal ε-(InₓGa₁₋ₓ)₂O₃ (x=0.05 and 0.15) on AlN by pulsed laser deposition (PLD) was performed for the first time. The PLD heater temperature and chamber oxygen pressure were systematically tuned to fine-tune the optimum growth parameter of ε-(InₓGa₁₋ₓ)₂O₃ on AlN. A heater temperature of 550 ℃ was the most suitable temperature to obtain the metastable hexagonal phase, avoiding polycrystallinity, suppressing the formation of cubic indium oxide, and inhibiting transformation to the monoclinic β-Ga₂O₃ phase. A chamber pressure of 1.25×10^-2 Torr was necessary to uniformly incorporate indium throughout the ε-Ga₂O₃ lattice and turn it into ε-(InₓGa₁₋ₓ)₂O₃. The X-ray diffraction (XRD) phi scans confirmed the hexagonal phase, and the epitaxial relationship was obtained to be (105) ε-(InₓGa₁₋ₓ)₂O₃ ∥ (103) AlN. The presence of indium in the ε-Ga₂O₃ was confirmed by XRD 2θ peak position shift and X-ray photoelectron spectroscopy via elemental scan depth profile with minor presence of unoxidized gallium atoms and oxygen vacancy centers. The measured bandgaps were 4.55 eV and 4.86 eV for ε-(In_0.15Ga_0.85)₂O₃ and ε-(In_0.05Ga_0.95)₂O₃, respectively.

DOI：

https://doi.org/10.1088/1361-6463/ae9d8e