A method of manufacturing a semiconductor substrate may include: forming a buffer layer on a growth substrate; forming a plurality of openings in the buffer layer, the plurality of openings penetrating through the buffer layer and being spaced apart from one another; forming a plurality of cavities on the growth substrate, the plurality of cavities being aligned to respectively correspond to the plurality of openings; growing a semiconductor layer on the buffer layer, the growing the semiconductor layer including filling the plurality of openings with the semiconductor layer; and separating the buffer layer and the semiconductor layer from the growth substrate, wherein a diameter of each of the plurality of openings at a boundary between the growth substrate and the buffer layer is smaller than a diameter of each of the plurality of cavities at the boundary.