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; the buffer layer is located on one side of the substrate, and the buffer layer comprises iron atoms; the blocking structure is located on the side, away from the substrate, of the buffer layer, and the blocking structure comprises at least one silicon nitride blocking layer; the channel structure comprises at least one channel layer, and the at least one channel layer is located on the side, away from the substrate, of the blocking structure; wherein the channel structure is in contact with the blocking structure and the buffer layer at the same time. According to the technical scheme, by arranging the silicon nitride barrier layer, the trailing effect of iron atoms in the channel structure can be reduced, the crystal quality of the channel layer can be improved, and then the quality of the epitax