A semiconductor laser device and manufacturing method of a semiconductor device

A method of fabricating a semiconductor laser device includes successively forming an active layer 3 and upper cladding layers 4, 6 on a lower cladding layer 2, etching away portions except regions of the upper cladding layers 4, 6 where a current flows to form a stripe-shaped ridge structure forming a buffer layer 8 comprising AlxGa1-xAs having an Al composition ratio x of 0 to 0.3 which is grown on surfaces of the upper cladding layers 4, 6 exposed by the etching, and forming a current blocking layer 9 comprising first conductivity type AlyGa1-yAs having an Al composition ratio y of 0.5 or more. Therefore, since the layer 8 comprises AlGaAs having a low Al composition ratio (0 SIMILAR 0.3), three-dimensional growth at the surface of the buffer layer 8 is suppressed, whereby the buffer layer 8 having reduced crystal defects is formed. Accordingly, the AlGaAs current blocking layer 9 also becomes a crystalline layer having reduced crystal defects and good crystalline quality. Consequently, current leakage is suppressed, whereby a laser having a low threshold current and a high efficiency can be fabricated.