Addressing the persistent challenges of heterostructure integration and low thermal conductivity in β-Ga2O3 devices, we report the epitaxial growth of single-crystalline BeO thin films on (2¯ 0 1) β-Ga2O3 substrates via plasma-enhanced atomic layer deposition. X-ray diffraction confirms the epitaxial growth of wurtzite (0 0 0 2) BeO films with well-defined out-of-plane and in-plane alignments, despite the dissimilar crystal structures. High-resolution transmission electron microscopy and fast Fourier transform analyses reveal a sharp BeO/ β-Ga2O3 interface and coherent crystallographic alignment. X-ray photoelectron spectroscopy demonstrates type-II band alignment with a valence-band offset of –0.5 eV and a conduction-band offset of 4.4 eV, distinct from the type-I alignment observed in non-epitaxial BeO/(0 0 1) β-Ga2O3 heterostructures. Electrical characterization shows that a Mo/(0 0 0 2) BeO/(2¯ 0 1) β-Ga2O3 MOS capacitor exhibits an exceptionally low leakage current density of 5.92 × 10-10A cm−2 at 1 MVcm−1 and minimal frequency dispersion in capacitance–voltage data, underscoring the excellent insulating properties and interface quality of epitaxial BeO films. This new route for epitaxial BeO growth on (2¯ 0 1) β-Ga2O3 holds strong promise for next-generation β-Ga2O3 heterostructure-based power electronics and ultraviolet optoelectronic devices.
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