Abstract: On a substrate of n-type GaAs are sequentially formed an n-type cladding layer (AlGaAs, Al content x=0.07, thickness t=2.86 &mgr;m), an n-type optical waveguide layer (GaAs, t=0.49 &mgr;m), an n-type carrier blocking layer (AlGaAs, x=0.40, t=0.03 &mgr;m), an active layer (composed of an In0.18Ga0.82As quantum well layer and a GaAs barrier layer), a p-type carrier blocking layer (AlGaAs, x=0.40, t=0.03 &mgr;m), a p-type optical waveguide layer (GaAs, t=0.49 &mgr;m), a p-type cladding layer (AlGaAs, x=0.20, t=1.08 &mgr;m), and a p-type cap layer (GaAs) in which a pair of n-type current blocking layers (GaAs) are buried. With this construction, the occurrence of a wavelength spit due to a higher-order mode can be inhibited thereby stabilizing a higher power operation.

Abstract: On an n-GaAs substrate are sequentially formed an n-GaAs buffer layer, an n-AlGaAs cladding layer, a non-doped InGaAs active layer, a p-AlxGa1−xAs cladding layer, a p-GaAs contact layer, and further an n-AlGaAs current blocking layer having a stripe-like window is embedded in the cladding layer. At the active layer side interface of the current blocking layer, a diffraction grating of cyclic bumps and dips shape is formed, but the diffraction grating is not formed in a region of the stripe-like window where the current blocking layer is not present, i.e., a current injection region. In this way, a semiconductor laser device of low oscillation threshold, high oscillation efficiency, high reliability, long life time, and stabilized oscillation wavelength can be realized.

Abstract: Optical guide layers are formed on both faces of the active layer, respectively, which optical guide layers have a band gap wider than that of the active layer, an n-type cladding layer and a p-type cladding layer respectively formed so as to sandwich the active layer and the optical guide layers therebetween, which cladding layers have a band gap wider than those of the optical guide layers, and carrier blocking layers are respectively formed between the active layer and the optical guide layers, which carrier blocking layers have a band gap wider than those of the active layer and the optical guide layers. The refractive index of the p-type cladding layer is lower than that of the n-type cladding layer. With such constitution inner losses are limited to a low level, as free carrier absorption is reduced, and the electric and thermal resistances of a semiconductor laser device are reduced, with the result that the laser device is enhanced in efficiency and output power.

Abstract: In a self-aligned structure semiconductor laser in which a pair of optical guide layers are respectively formed on both faces of an active layer, the optical guide layers having a bandgap which is wider than that of the active layer, a pair of cladding layers are formed so as to sandwich the active layer and the optical guide layers, the cladding layers having a bandgap which is wider than bandgap of the optical guide layers, a pair of carrier blocking layers are respectively formed between the active layer and the optical guide layers, the carrier blocking layers having a bandgap which is wider than bandgaps of the active layer and the optical guide layers, and a current blocking layer having a stripe-like window is embedded in at least one of the optical guide layers, the current blocking layer is formed by selective growth. In this way, a window of a current blocking layer can be accurately formed and the fabrication yield can be improved while avoiding maleffects on other layers.

Abstract: A semiconductor device including a buffer layer 32 on n-GaAs, a clad layer 31, a wave guide layer 30 and a carrier block layer 29 of n-AlGaAs, a side barrier layer 28 of non-doped AlGaAs, an active layer 27 which is formed by two non-doped GaAs quantum well layers and a barrier layer of AlGaAs, a side barrier layer 26 of non-doped AlGaAs, a carrier block layer 25, a wave guide layer 23 and a clad layer 22 of p-AlGaAs, and a cap layer 21 of p-GaAs are grown in this order. Inside the wave guide layer 23, current blocking layers 24 having a lower refractive index and higher Al-composition than that of the wave guide layer and sandwich a strip-shaped active region 34. This creates a refractive index difference between the active region 34 and buried regions 33 in which each of the current blocking layers 24 exists, thereby forming a refractive index guide structure. Thus, it is possible to obtain a high-output semiconductor laser device of the refractive index guided type which is easy to manufacture.

Abstract: As shown in FIG. 1, on a semiconductor substrate 20 formed in sequence are a second n-type clad layer 11, a first n-type clad layer 12, an n-type carrier blocking layer 13, an active layer 14, a p-type carrier blocking layer 15, a first p-type clad layer 16, a second p-type clad layer 17, a current constriction layer 18, and a p-type contact layer 19. The carrier blocking layers 13 and 15 are doped to a high doping concentration of more than 1.times.10.sup.18 cm.sup.-3. The first clad layers 12 and 16 and the second clad layers 11 and 17 are doped to a low doping concentration of less than 3.times.10.sup.17 cm.sup.-3. The p-type carrier blocking layer 15 is doped with carbon or magnesium which is low in the diffusivity. Accordingly, the carriers are successfully confined in the active layer 14 thus to suppress the internal loss and the electrical resistance, whereby a high-efficiency, high-output semiconductor laser device can be obtained.