A preparation method of an aluminum nitride (AlN) composite structure based on a two-dimensional (2D) crystal transition layer is provided. The preparation method includes: transferring the 2D crystal transition layer on a first periodic groove of an epitaxial substrate; forming a second periodic groove staggered with the first periodic groove on the 2D crystal transition layer; depositing a supporting protective layer; depositing a functional layer of a required AlN-based material; and removing the 2D crystal transition layer through thermal oxidation to obtain a semi-suspended AlN composite structure. The preparation method has low difficulty and is suitable for large-scale industrial production. Design windows of the periodic grooves and the AlN functional layer are large and can meet the material requirements of deep ultraviolet light-emitting diodes (DUV-LEDs) and radio frequency (RF) electronic devices for different purposes, resulting in a wide application range.

Methods for transferring graphene to substrates include at least a method for transferring a graphene-metal bilayer to a substrate to form a laminate thereof. The method can include applying a first continuous polymer layer to a graphene layer of the graphene-metal bilayer; applying a first discontinuous polymer layer to the first continuous polymer layer; applying a second continuous polymer layer to a metal layer of the graphene-metal bilayer; applying a second discontinuous polymer layer to the second continuous polymer layer; etching the first continuous polymer layer with a first etchant through the first discontinuous polymer layer; laminating the substrate by pressing the face of the graphene layer into a surface of the substrate; etching the second continuous polymer layer with a second etchant through the second discontinuous polymer layer, thereby transferring the graphene-metal bilayer to the substrate to form the laminate.