Preparation method of aluminum nitride composite structure based on two-dimensional (2D) crystal transition layer

A preparation method of an aluminum nitride (AlN) composite structure based on a two-dimensional (2D) crystal transition layer, comprising the following steps:

• 1) Providing an epitaxial substrate;
• 2) Forming a first periodic groove on a surface of the epitaxial substrate by a mask etching technique, wherein a zone outside the first periodic groove on the epitaxial substrate is a first non-groove zone, and a depth of the first periodic groove is less than a thickness of the epitaxial substrate;
• 3) Transferring the 2D crystal transition layer to the surface of the epitaxial substrate on which the first periodic groove is located to cover the first periodic groove and the first non-groove zone on the epitaxial substrate to produce a layer structure;
• 4) Etching a part of the 2D crystal transition layer on the first non-groove zone by the mask etching technique to form a second periodic groove, wherein a zone outside the second periodic groove on the 2D crystal transition layer is a second non-groove zone;
• a depth of the second periodic groove is equal to a thickness of the 2D crystal transition layer;
• a period of the second periodic groove is equal to a period of the first periodic groove;
• the second periodic groove is parallel to the first periodic groove;
• and a planar projection of the second periodic groove falls in the first non-groove zone;
• 5) Depositing a supporting protective layer on a surface of the second non-groove zone of the 2D crystal transition layer to enhance a mechanical strength of the 2D crystal transition layer and prevent a collapse at a position of the first periodic groove during subsequent deposition of an AlN functional layer, wherein a plane shape of the supporting protective layer is consistent with a plane shape of the second non-groove zone;
• 6) Depositing an AlN-based material on a surface of the supporting protective layer, such that the AlN-based material fills a space between the second periodic groove and the supporting protective layer and covers a part of the supporting protective layer corresponding to the second periodic groove and the second non-groove zone to form a functional layer;
• 7) Removing the 2D crystal transition layer through thermal oxidation to obtain a semi-suspended functional layer;
• and
• 8) Depositing a surface-conductive layer on the semi-suspended functional layer to obtain the AlN composite structure.