In formation of a quantum dot structure in a light emitting layer, a matrix region (an n-type conductive layer and matrix layers) is formed on a growth underlying layer of AlN whose abundance ratio of Al is higher (or whose lattice constant is smaller) than that in the matrix region by an MBE technique, thereby to realize conditions where compression stress is caused in an in-plane direction perpendicular to the direction of growth of the matrix region, and then to form island crystals by self-organization in the presence of this compression stress. The compression stress inhibits an increase in lattice constant caused by the reduced abundance ratio of Al in the matrix region, i.e., to compensate for a difference in lattice constant between the island crystals and the matrix region. The compression stress functions to enlarge compositional limits for formation of the island crystals by self-organization to the Ga-rich side.