Light-emitting semiconductor devices comprising a substrate and a p-n junction structure formed on the substrate are described. The p-n junction structure is made of a combination of a wide gap semiconductor layer made of a p-type chalcopyrite semiconductor of the formula, (Cu.sub.a Ag.sub.1-a)(Al.sub.b Ga.sub.1-b)(Se or S).sub.2 wherein 0.ltoreq.a.ltoreq.1 and 0.ltoreq.b.ltoreq.1, and an n-type II-VI semiconductor of the formula, (Zn.sub.c Cd.sub.1-c)(S.sub.d Se.sub.1-d or Se.sub.d Te.sub.1-d) wherein 0.ltoreq.c.ltoreq.1 and 0.ltoreq.d.ltoreq.1. By this, light-emitting diodes are obtained. When an active layer is provided between the n and p-type layers, semiconductor laser devices are obtained. These devices are capable of emitting blue light to UV light.