【Epitaxy Papers】Lattice-matched (AlₓScᵧGa₁₋ₓ₋ᵧ)₂O₃/β-Ga₂O₃ heterostructures with widely tunable bandgap

      Researchers from Institute of Science Tokyo have published a dissertation titled " Lattice-matched (Al_xSc_yGa_1−x−y)₂O₃/β-Ga₂O₃ heterostructures with widely tunable bandgap " in Applied Physics Letters.

Abstract

      Bandgap engineering of β-Ga₂O₃ is essential for advancing its electronic and optoelectronic applications. However, the growth of high-quality heteroepitaxial structures is often hampered by large lattice mismatches. In this study, we design (Al_xSc_yGa_1−x−y)₂O₃ quaternary alloys in the form of both polycrystalline powders and heteroepitaxial films and demonstrate their lattice matching to β-Ga₂O₃. Powder x-ray diffraction (XRD) measurements reveal that the lattice parameters of monoclinic (Al_xSc_yGa_0.8)₂O₃ match those of β-Ga₂O₃ when x/y = 1.5–3.2. (Al_xSc_yGa_1−x−y)₂O₃ thin films are grown on β-Ga₂O₃ (100) substrates by pulsed-laser deposition by varying the composition ratio x/y and the total substitutional fraction x + y. Nearly perfect lattice-matched epilayers with uniform composition and crystal structure are obtained up to x + y ∼ 0.6, as confirmed by XRD and scanning transmission electron microscopy. Electron energy loss spectroscopy reveals a tunable bandgap from 4.5 to 5.8 eV. These results demonstrate that (AlxScyGa_1−x−y)₂O₃/β-Ga₂O₃ heterostructures are promising platforms for ultrawide-bandgap semiconductor devices.

DOI：

https://doi.org/10.1063/5.0326523