According to at least some embodiments of the present disclosure, a method of manufacturing semiconductor wafers comprises: selectively growing a nitride buffer layer on a first surface of a patterned substrate, the patterned substrate including at least the first surface and a second surface; and growing an epitaxial layer on the nitride buffer layer, wherein a crystal surface of the epitaxial layer grows along a normal direction of the patterned substrate. The epitaxial layer does not include multiple crystal surfaces having different crystal growth directions that cause a stress at a junction interface where the crystal surfaces having the different crystal growth directions meet.