PURPOSE: To enable the realization of a semiconductor laser possessed of an oscillation frequency in a blue light range of 490-400nm by a method wherein a double hetero-structure is provided, where an active layer is formed of Cu(AlaGa1-a)(SbbSe1-b)2 and clad layers are formed of P-type Cu(AlaGa1-a)(SbbSe1-b)2 and N-type (ZnoCd1-o)(SdSe1-d) respectively whose forbidden bandwidths are both larger than that of the active layer.

CONSTITUTION: An N-type clad layer 2 of N-type Zn(S0.05Se0.15) whose lattice constant is coincident with the lattice constant a=5.449A of GaP is formed by growth on an N-type GaP substrate 1. The forbidden bandwidth of the clad layer 2 is 3.6eV or so. An active layer 3 of Cu(Al0.70Ga0.22)(Sb0.50Se0.42)2 whose lattice constant is coincident with that of GaP is formed by growth on the clad layer 2. Moreover a P-type CuAl(Sb0.50Se0.42)2 clad layer 4 whose lattice constant is coincident with that of Gap is formed on the active layer 3. The forbidden bandwidth of the clad layer 4 is 3.1eV or so. The difference between the forbidden bandwidths Eg1 and Eg2 of the active layer 3 and the clad layer 4 is 200meV or so (Eg1<Eg2), which bandwidth difference is enough for laser oscillation, and an oscillation wavelength of 420nm or so can be obtained.