PURPOSE: To reduce the warpage of a substrate and any crack produced in a grown layer by forming grooves in the thin grown layer to form a plurality of islands in the same, and further growing the layer by a vapor phase epitaxy process.

CONSTITUTION: GaAs is grown on a Si substrate 11 by an ordinary process to form a GaAs layer 12a. Grooves 16 are formed in the GaAs layer 12a by etching with use of a resist mask to provide the GaAs layer in a plurality of islands. After the mask 15 is removed, the GaAs is further grown by a vapor phase epitaxy process, for example by a MOCVD process to form a GaAs layer 12b. The GaAs layer 12 is divided along the grooves 16 and forms island- like regions. Hereby, warpage of the substrate 11 and any crack in the grown layer, i.e., in the GaAs layer 12 are reduced.