Abstract: In a process for producing a substrate for use in a semiconductor element: a first GaN layer having a plurality of pits at its upper surface is formed; and then a second GaN layer is formed by growing a GaN crystal over the first GaN layer until the upper surface of the second GaN layer becomes flattened. Each of the above plurality of pits has an opening area of 0.005 to 100 &mgr;m2 and a depth of 0.1 to 10.0 &mgr;m.

Abstract: In a semiconductor laser device including an active region which is made of an aluminum-free material and a plurality of cladding layers made of at least one AlGaAs or AlGaInP material, the active region includes a quantum well layer and at least one optical waveguide layer; a portion of the at least one optical waveguide layer located on one side of the quantum well layer has a thickness of 0.25 &mgr;m or more; and the at least one optical waveguide layer, other than a portion of the at least one optical waveguide layer being located near the quantum well layer and having a thickness of at least 10 nm, is doped with impurity of 1017 cm−3 or more.

Abstract: In a semiconductor-laser device: an n-type cladding layer, an optical-waveguide layer, an Inx3Ga1−x3As1−y3Py3 compressive-strain quantum-well active layer (0<x3≦0.4, 0≦y3≦0.1), an optical-waveguide layer, a p-Inx6Ga1−x6P etching-stop layer (0≦x6≦1), a p-Inx1Ga1−x1As1−y1Py1 etching-stop layer (0≦x1≦0.4, 0≦y1≦0.5), a p-InxGa1−xP layer (x=0.49±0.01), and an n-InxGa1−xP current-confinement layer are formed on an n-GaAs substrate. A stripe groove is formed down to the depth of the upper surface of the p-Inx6Ga1−x6P etching-stop layer. A p-Inx4Ga1−x4As1−y4Py4 cladding layer (x4=0.49y4±0.01, x−0.04≦x4≦x−0.01) is formed over the current-confinement layer and the stripe groove. A p-type contact layer is formed on the p-Inx4Ga1−x4As1−y4Py4 cladding layer. The absolute value of the product of the strain and the thickness of the active layer does not exceed 0.

Abstract: In a semiconductor laser device, a lower cladding layer, a lower optical waveguide layer, an active layer, an upper optical waveguide layer, an upper cladding layer, and a contact layer are formed in this order on a GaAs substrate. The semiconductor laser device has at least one of first and second resistance reduction layers. The first resistance reduction layer is arranged between the substrate and the lower cladding layer, and made of an InGaAsP material having an energy gap which is greater than the energy gap of the substrate, and smaller than the energy gap of the lower cladding layer. The second resistance reduction layer is arranged between the upper cladding layer and the contact layer, and made of an InGaAsP material having an energy gap which is greater than the energy gap of the contact layer, and smaller than the energy gap of the upper cladding layer.

Abstract: A semiconductor laser element capable of reducing an element resistance and producing a beam of high quality includes: an n-Ga1−Z4AlZ4N composition gradient layer provided between an n-GaN contact layer and an n-Ga1−Z1AlZ1N/GaN superlattice clad layer; an n-Ga1−Z5AlZ5N composition gradient layer provided between the n-Ga1−Z1AlZ1N/GaN superlattice clad layer and an n- or i-Ga1−Z2AlZ2N optical waveguide layer; a p-Ga1−Z5AlZ5N composition gradient layer provided between a p- or i-Ga1−Z2AlZ2N optical waveguide layer and a p-Ga1−Z1AlZ1N superlattice gradient layer; and a p-Ga1−Z4AlZ4N composition gradient layer provided between a p-Ga1−Z1AlZ1N/GaN superlattice upper clad layer and a p-GaN contact layer. Z4 of the n-Ga1−Z4AlZ4N composition gradient layer is continuously changed from 0 to a composition corresponding to the band gap of the Ga1−Z1AlZ1N/GaN superlattice clad layer.

Abstract: In a process for producing a substrate for use in a semiconductor element: a growth suppression mask which is constituted by a plurality of mask elements being discretely arranged and each having a width of 2.5 micrometers or smaller is formed on a surface of a base substrate; a first GaN layer having a plurality of holes is formed on the surface of the base substrate by growing GaN from areas of the surface of the base substrate which are not covered by the plurality of first mask elements; and a second GaN layer is formed over the first GaN layer by crystal growth.

Abstract: In a semiconductor laser device: a lower cladding layer; a lower optical waveguide layer; a compressive strain quantum well active layer made of Inx3Ga1−x3As1−y3Py3, where 0<x3≦0.4, 0≦y3≦0.1; an upper optical waveguide layer; a first upper cladding layer made of Inx8Ga1−x8P of a second conductive type, and formed on the upper optical waveguide layer; an etching stop layer made of Inx1Ga1−x1As1−y1Py1 of the second conductive type, where 0≦x1≦0.3, 0≦y1≦0.3; a current confinement layer made of Inx8Ga1−x8P of the first conductive type, where x8=0.49±0.01; a second upper cladding layer made of Alz4Ga1−z4As of the second conductive type, where 0.20≦z4≦0.50; and a contact layer of the second conductive type are formed on a GaAs substrate of a first conductive type in this order.

Abstract: In a process for producing a substrate for use in a semiconductor element: a porous anodic alumina film having a great number of minute pores is formed on a surface of a base substrate; the surface of the base substrate is etched by using the porous anodic alumina film as a mask so as to form a great number of pits on the surface of the base substrate; the porous anodic alumina film is removed; and a GaN layer is formed on the surface of the base substrate by crystal growth.

Abstract: In a semiconductor laser device: an n-type lower cladding layer; a lower optical waveguide layer; a compressive strain quantum well active layer made of Inx3Ga1-x3As1-y3Py3, where 0<x3≦0.4 and 0≦y3≦0.1; an upper optical waveguide layer; a p-type In0.49Ga0.51P first upper cladding layer; an etching stop layer made of Inx1Ga1-x1As1-y3Py1, where 0≦x1≦0.3 and 0≦y1≦0.6; an n-type In0.49Ga0.51P current confinement layer; a p-type second upper cladding layer made of Inx4Ga1-x4As1-y4Py4, where x4=(0.49±0.01)y4 and 0.4≦x4≦0.46; and a p-type contact layer are formed on an n-type GaAs substrate in this order. At least the current confinement layer has a stripe-shape opening realizing a current injection window filled with the second upper cladding layer. The absolute value of the product of the strain and the thickness of the compressive strain quantum well active layer is equal to or smaller than 0.

Abstract: In a semiconductor laser device, a lower cladding layer, a lower optical waveguide layer, an active layer, an upper optical waveguide layer, an upper cladding layer, and a contact layer are formed in this order on a GaAs substrate. The semiconductor laser device has at least one of first and second resistance reduction layers. The first resistance reduction layer is arranged between the substrate and the lower cladding layer, and made of an InGaAsP material having an energy gap which is greater than the energy gap of the substrate, and smaller than the energy gap of the lower cladding layer. The second resistance reduction layer is arranged between the upper cladding layer and the contact layer, and made of an InGaAsP material having an energy gap which is greater than the energy gap of the contact layer, and smaller than the energy gap of the upper cladding layer.

Abstract: In a semiconductor-laser device: an n-type cladding layer, an optical-waveguide layer, an Inx3Ga1−x3As1−y3Py3 compressive-strain quantum-well active layer (0<x3≦0.4, 0≦y3≦0.1), an optical-waveguide layer, a p-Inx6Ga1−x6P etching-stop layer (0≦x6≦1), a p-Inx1Ga1−x1As1−y1Py1 etching-stop layer (0≦x1≦0.4, 0≦y1≦0.5), a p-InxGa1−xP layer (x=0.49±0.01), and an n-InxGa1−xP current-confinement layer are formed on an n-GaAs substrate. A stripe groove is formed down to the depth of the upper surface of the p-Inx6Ga1−x6P etching-stop layer. A p-Inx4Ga1−x4As1−y4Py4 cladding layer (x4=0.49y4±0.01, x−0.04≦x4≦x−0.01) is formed over the current-confinement layer and the stripe groove. A p-type contact layer is formed on the p-Inx4Ga1−x4As1−y4PY4 cladding layer. The absolute value of the product of the strain and the thickness of the active layer does not exceed 0.

Abstract: A semiconductor laser element capable of reducing an element resistance and producing a beam of high quality includes: an n-Ga1-Z4AlZ4N composition gradient layer provided between an n-GaN contact layer and an n-Ga1-Z1AlZ1N/GaN superlattice clad layer; an n-Ga1-Z5AlZ5N composition gradient layer provided between the n-Ga1-Z1AlZ1N/GaN superlattice clad layer and an nor i-Ga1-Z2AlZ2N optical waveguide layer; a p-Ga1-Z5AlZ5N composition gradient layer provided between a p- or i-Ga1-Z2AlZ2N optical waveguide layer and a p-Ga1-Z1AlZ1N superlattice gradient layer; and a p-Ga1-Z4AlZ4N composition gradient layer provided between a p-Ga1-Z1AlZ1N/GaN superlattice upper clad layer and a p-GaN contact layer. Z4 of the n-Ga1-Z4AlZ4N composition gradient layer is continuously changed from 0 to a composition corresponding to the band gap of the Ga1-Z1AlZ1N/GaN superlattice clad layer.

Abstract: A semiconductor laser includes a first clad layer having one of p-type conductivity and n-type conductivity, a first optical waveguide layer, a first barrier layer of GaAs1-y2Py2, a quantum-well active layer of Inx3Ga1-x3As1-y3Py3, a second barrier layer of GaAs1-y2Py2, a second optical waveguide layer and a second clad layer having the of p-type conductivity and n-type conductivity formed in this order on a GaAs substrate. Each of the first and second clad layers is of a composition which matches with the GaAs substrate in lattice. Each of the first and second optical waveguide layers is of a InGaAsP composition which matches with the GaAs substrate in lattice. Each of the first and second barrier layers is 10 to 30 nm in thickness and is of a composition which has tensile strain relative to the GaAs substrate, the product of the tensile strain and the thickness of each of the first and second barrier layers being 5 to 20% nm.

Abstract: In a semiconductor laser device, an active region includes alternating layers of at least one quantum well layer and a plurality of barrier layers, where two of the plurality of barrier layers are the outermost layers of the alternating layers, each of the at least one quantum well layer has a first thickness da and a compressive strain &Dgr;a, and each of the plurality of barrier layers has a second thickness db and a tensile strain &Dgr;b. In the active region, a strain buffer layer is formed between each quantum well layer and each of two barrier layers adjacent to the quantum well layer, where each strain buffer layer has a third thickness dr and an intermediate strain &Dgr;r which is between the compressive strain &Dgr;a and the tensile strain &Dgr;b.

Abstract: A semiconductor laser device comprises a GaAs substrate, a first cladding layer having either one of p-type electrical conductivity and n-type electrical conductivity, a first optical waveguide layer, an In.sub.x2 Ga.sub.1-x2 As.sub.1-y2 P.sub.y2 first barrier layer, an In.sub.x3 Ga.sub.1-x3 As.sub.1-y3 P.sub.y3 quantum well active layer, an In.sub.x2 Ga.sub.1-x2 As.sub.1-y2 P.sub.y2 second barrier layer, a second optical waveguide layer, and a second cladding layer having the other electrical conductivity, the layers being overlaid in this order on the substrate. Each cladding layer and each optical waveguide layer have compositions, which are lattice matched with the substrate. Each of the first and second barrier layers has a tensile strain with respect to the substrate and is set such that a total layer thickness of the barrier layers may be 10 nm to 30 nm, and a product of a strain quantity of the tensile strain and the total layer thickness may be 0.05 nm to 0.2 nm.

Abstract: A III-V group semiconductor laser includes a first clad layer, a first optical waveguide layer, a first barrier layer, an active layer, a second barrier layer, a second optical waveguide layer and a second clad layer formed in this order on a GaAs substrate which is a III-V group compound semiconductor. Each of the first and second clad layers and the first and second optical waveguide layers is of a composition which matches with the GaAs substrate in lattice. The active layer is of a composition which induces compressive strain on the GaAs substrate. Each of the first and second barrier layers is of a composition which induces tensile strain on the GaAs substrate, thereby compensating for the compressive strain induced in the active layer. The ratio of V group elements contained in the first optical waveguide layer is the same as that in the first barrier layer, and the ratio of V group elements contained in the second optical waveguide layer is the same as that in the second barrier layer.

Abstract: A semiconductor laser includes a first clad layer, a first optical waveguide layer, a first barrier layer, an active layer, a second barrier layer, a second optical waveguide layer and a second clad layer formed in this order on a GaAs substrate which is a III-V group compound semiconductor. Each of the layers contains As and P, each of the first and second clad layers and the first and second optical waveguide layers is of a composition which matches with the GaAs substrate in lattice. The active layer is of a composition which induces compression strain on the GaAs substrate, and each of the first and second barrier layers is of a composition which induces tensile strain on the GaAs substrate, thereby compensating for the compression strain induced in the active layer.