Epitaxial Growth of β-Ga₂O₃ Thin Films on Si with YSZ Buffer Layer

We report the epitaxial growth of (2̅01)-oriented β-Ga₂O₃ thin films on a (001) Si substrate using the pulsed laser deposition technique employing epitaxial yttria-stabilized zirconia (YSZ) buffer layers. Epitaxial β-Ga₂O₃ thin films possess a biaxial compressive strain on YSZ single-crystal substrates while they exhibit a biaxial tensile strain on YSZ-buffered Si substrates. Post-annealing improves the crystalline quality of β-Ga₂O₃ thin films. High-resolution X-ray diffraction analyses reveal that the epitaxial (2̅01) β-Ga₂O₃ thin films on Si have eight in-plane domain variants to accommodate the large difference in the crystal structure between monoclinic β-Ga₂O₃ and cubic YSZ. The results provide a pathway to integrate epitaxial β-Ga₂O₃ thin films on a Si gold standard substrate, which will expand the application scope beyond high-power electronics.