PURPOSE: To enhance the effect of multiquantum barriers by a method wherein semiconductor layer having a larger band gap than another semiconductor layer having a smaller band gap is to be doped with more dopant than that of the latter.

CONSTITUTION: A structure comprising an n-GaAs buffer layer 2, an n-GaInP buffer layer 3, an n-AlGaInP clad layer 4, a GaInP active layer 5, a multiquantum barrier (MQB) layer 6, a p-AlGaInP clad layer 7 and a p-GaAs cap layer 8 is successively grown and formed on an n-GaAs substrate 1. At this time, the MQB structure is composed of 20 pairs of a p-AlGaInP barrier layer 11 (carrier concentration of 5×1018cm-3) and a p-GaInP well layer 10 (carrier concentration of 1-2×1018cm13). Through these procedures, the whole barrier layers of MQB are doped with more p type dopant than that of well layer so that the level of MQB to the electrons of conductive band may be increased thereby enabling the electron confinement and the hole feed efficiency to be improved.