▎ 摘　　要

NOVELTY - Preparing single crystal substrate, comprises (1) providing substrate and forming porous structure on surface of the substrate, (2) depositing barrier layer and covering the top surface of porous structure and inner surface of the porous structure, (3) removing the barrier layer on top surface of the porous structure to expose the top surface of porous structure, and (4) performing epitaxial growth of single crystal layer on porous structure and separating the substrate, where the single crystal layer grows from the top surface of porous structure, and the barrier layer is used to suppress single crystal layer growth on the inner surface of the porous structure. The substrate is a sapphire substrate, the porous structure is gallium nitride porous layer and the barrier layer is silicon nitride, silica and/or graphene. USE - The method is useful for preparing single crystal substrate. ADVANTAGE - The method: enables epitaxially grown single crystal layer to form weak connection with the substrate through the porous structure by using porous structure and thus ensures the single crystal layer and the substrate have high separation yield.