A thin layer structure includes a substrate, a blocking pattern that exposes part of an upper surface of the substrate, and a single crystalline semiconductor layer on the part of the upper surface of the substrate exposed by the pattern and in which all outer surfaces of the single crystalline semiconductor layer have a crystallographic orientation. The thin layer structure is formed by an SEG process in which the temperature is controlled to prevent migration of atoms in directions towards the central portion of the upper surface of the substrate. Thus, sidewall surfaces of the layer will not be constituted by facets.