Semiconductor device

The present disclosure provides a semiconductor device which includes a base layer and a buffer structure. The base layer includes a first semiconductor compound having a first lattice constant and including a plurality of elements, and an atomic radius of one of the plurality of elements which has the largest atomic radius is defined as a first atomic radius. The buffer structure includes a second semiconductor compound and a first additive. The second semiconductor compound has a second lattice constant and the first additive has a second atomic radius. The second lattice constant is larger than the first lattice constant, and the second atomic radius is larger than the first atomic radius.