PURPOSE: To obtain a high-efficiency laser device, by allowing a small-reflectivity layer to grow on an activation layer by the first phase epitaxial growth, allowing growth only inside of a narrow-width groove, which is kept apart by prescribed width and in parallel, by the second phase epitaxial growth and embedding side surfaces.

CONSTITUTION: An n-type Al0.3Ga0.7As 7, a GaAs activation layer 8 and a p-type Al0.3Ga0.7As 9 are epi-formed on an n-type GaAs 6, and by etching the layer 7 through 9, grooves of approximately 20μm in width are provided on both sides of a belt-like layer of approximately 5mm in width. After washing crystllized surface, a p-type Al0.3Ga0.7As 10 and an n-type Al0.3Ga0.7As 11 are epi-formed. By using a constant growth speed and a constant cooling speed, the crystallized surface is flatly formed. Since there is no more epi-formation on AlGaAs having been once aerated, surface of the layer 9 is free from growth layer. Electrodes 13 and 14 are formed, and when the electrode 14 is driven as positive, the layers 11 and 10 are conversely biased and the most part of the current needed for radiation of the activation layer is caught by a layer 15, and therefore, a laser of high conversion efficiency can be obtained.