An epitaxial light emitting structure includes n-type and p-type semiconductor layers, and a light emitting component disposed therebetween. The light emitting component includes a multiple quantum well structure which contains a plurality of first periodic layered elements, each of which includes first, second and third layers alternately stacked on one another. For each of the first periodic layered elements, the first, second and third layers respectively have a first energy bandgap (Eg1), a second energy bandgap (Eg2), and a third energy bandgap (Eg3) that satisfy a relationship of Eg1