Epitaxial structure of semiconductor device and manufacturing method thereof, and semiconductor device

An epitaxial structure of a semiconductor device comprising:

• a substrate;
• and
• an epitaxial layer located on one side of the substrate, the epitaxial layer comprising at least a first sub-epitaxial layer group, the first sub-epitaxial layer group comprising a first sub-epitaxial layer and a second sub-epitaxial layer arranged in a stack, wherein the second sub-epitaxial layer is located on one side of the first sub-epitaxial layer opposite the substrate, wherein a surface of one side of the first sub-epitaxial layer opposite the substrate comprises a plurality of first dislocation pits, wherein sidewalls of the first dislocation pits intersect both a plane where the first sub-epitaxial layer is located and a first direction, wherein the first direction is parallel to a direction in which the first sub-epitaxial layer points towards the second sub-epitaxial layer, and wherein the second sub-epitaxial layer grows along the sidewalls of the first dislocation pits, and covers at least the sidewalls of the first dislocation pits;
• wherein, along the first direction, depth of the first dislocation pit is h, wherein thickness of the first sub-epitaxial layer is H1, and wherein thickness of the second sub-epitaxial layer is H2:
• wherein 5 nm≤h≤60 nm and H1>100 nm;
• wherein H2>h;
• and
• wherein 1/20H1<h≤1/2H1.