PURPOSE: To obtain a distorted quantum well laser of a structure, wherein the interface between a well layer and a barrier layer is formed into a steep interface in the order of atomic layer scale, by a method wherein prior to the growth of the well layer and the barrier layer of a distorted quantum well structure, the growth surfaces of the well and barrier layers are exposed to a sulfur-containing gas plasma.

CONSTITUTION: A buffer layer 11 is grown on the surface of a substrate 10, subsequently, a first light guide layer 12 is grown and after this, a plasma treatment using sulfur-containing gas, such as S2F2 gas, is performed on the growth surfaces of the layers 11 and 12. After the plasma treatment, the growth surfaces are heated to remove a sulfur film. Then, after a well layer 13 is grown, a second plasma treatment using a sulfur-containing gas is again performed. After this, a barrier layer 14 is grown and a plasma treatment in the formation of the layers 14 and 13 and the formation of each layer is repeatedly performed to form an active layer 20, which is formed into a distorted quantum well structure having 4 layers of wells. After that, a second light guide layer 15, a clad layer 16 and a contact layer 17 are grown and moreover, an electrode is formed to obtain a distorted quantum well laser.