Composite single crystal piezoelectric substrate and preparation method thereof

The invention discloses a composite single-crystal piezoelectric substrate and a preparation method thereof. The composite single-crystal piezoelectric substrate comprises a silicon substrate layer (1), a silicon dioxide layer (2) and a single-crystal piezoelectric layer (3), wherein the surface of the silicon substrate layer (1) is damaged to form a damaged layer (4), and the damaged layer (4) is in contact with the silicon dioxide layer (2). According to the method provided by the invention, a high-temperature process step is set before the damaged layer (4) is formed, and the damaged layer (4) is prepared through the silicon dioxide layer (2) in a remote distance manner, so the thickness uniformity of the silicon dioxide layer (2) is good, the defect density for capturing carriers in the damaged layer (4) is large, the structure of the composite single crystal piezoelectric substrate is stable, carriers generated due to inevitable defects on the interface of the silicon substrate layer (1) and the silicon