A patterned epitaxial substrate includes a substrate and a plurality of patterns. The substrate has a first zone and a second zone surrounding the first zone. The first zone is disposed around a center of the substrate. The patterns and the substrate are integrally formed, and the patterns are disposed on the substrate. The patterns include a plurality of first patterns and a plurality of second patterns. The first patterns are disposed in the first zone. The second patterns are disposed in the second zone. Sizes of the first patterns are different from sizes of the second patterns.