PURPOSE: To obtain a semiconductor laser wherein heat generation due to contact resistance does not occur, by forming junction layers capable of reducing contact resistance, between a clad layer and an electrode.

CONSTITUTION: In order to reduce contact resistance, a first junction layer 17 (nitrogen-doped Zn0.25Cd0.75S, thickness 0.1μm) and a second junction layer 18 (nitrogen doped Zn0.25Hg0.75S, thickness 0.1μm) are formed between a second clad layer 13 and a second conductivity type electrode 15. Thereby the forbidden bandwidth can be narrowed. Further contact resistance can be reduced by forming the junction layers of material wherein defect due to mismatching with lattice constants of a substrate 10 is not generated. Since the forbidden bandwidth of the second junction layer 18 is small to be nearly equal to that of gallium aarsenide of a substrate 10, low contact resistance can be expected by doping concentration of about 1018cm-3. In the above case, a composition matched in lattice with the substrate 10 can be obtained in the first junction layer 17 and the second junction layer 18, by about 25% zinc ratio of group II component composition. Thereby dislocation defect due to lattice distortion is not generated.