Epitaxial structure of semiconductor device, preparation method of epitaxial structure and semiconductor device

The embodiment of the invention provides an epitaxial structure of a semiconductor device, a preparation method of the epitaxial structure and the semiconductor device. The epitaxial structure comprises a substrate, a buffer structure and an insertion structure, the buffer structure comprises at least two buffer layers, the insertion structure comprises at least one insertion layer, the buffer layers and the insertion layers are alternately laminated, and any insertion layer is located between two adjacent buffer layers; at least one insertion layer comprises a plurality of island-shaped structures, and the buffer layer located on the side, away from the substrate, of the island-shaped structures covers the island-shaped structures. By adopting the technical scheme, the pressure stress generated in the growth process of the epitaxial layer can be controlled by arranging the insertion structure, so that the warping of the substrate in the growth process can be reduced, the thickness uniformity of the buffer la