Abstract: According to the present invention, a high-efficiency and high reliability GaN-based semiconductor light emitting device having uniform light emission from the active layer, can be obtained by suppressing the defect density of the interface between the guide layer and cladding layer. When manufacturing the GaN-based semiconductor light emitting device, the growth temperature and pressure are increased, or the carrier gas flow rate and ammonia flow rate necessary for efficiently growing p-GaAlN are increased, in the vicinity of the interface between the upper p-GaN guide layer and p-AlGaN cladding layer in particular, and thus a method and structure, capable of suppressing these high defect densities generated, can be provided.

Abstract: In the semiconductor light emitting device, a high resistance layer formed by mutual diffusion at an interface with the substrate crystal can be eliminated, and a low resistance p-type contact can be realized. In addition, it is possible to reduce the leak current when an internal current-blocking structure is formed. In practice, a compound semiconductor layer offset in composition ratio stoichiometrically is used as the contact layer. Further, when a predetermined element is added to the contact layer, a large amount of doping can be enabled in comparison with when impurities are added to the ordinary GaN based layer. Therefore, a high concentration conductive type layer can be realized while reducing the contact resistance. In addition, when the compound semiconductor layer offset away from the stoichiometric composition is used as the current-blocking layer, the current-blocking efficiency can be improved.

Abstract: A semiconductor laser is disclosed, which realizes a continuous oscillation in a fundamental transverse mode at a low operating voltage by a transverse mode control. This semiconductor laser is fabricated by forming successively the following layers on a sapphire substrate 10 in the order an n-type GaN contact layer, an n-type GaAlN cladding layer 13, an MQW active layer 16, a p-type GaAlN cladding layer 19, wherein the laser comprises a double heterostructure including a ridge in the shape of a stripe formed in the cladding layer 19 and a light confining layer 20 formed in a region except the ridge portion of the cladding layer 19 on the double heterostructure, wherein a refractive index of the light confining layer 20 is larger than that of a p-type GaAlN cladding layer.

Abstract: A gallium nitride-based compound semiconductor laser has a double-heterojunction structure, in which an active layer is sandwiched between cladding layers, on a sapphire substrate. A GaN current blocking layer having a striped opening portion is formed on the p-cladding layer. A p-GaN buried layer and a contact layer through which a current is injected into the opening portion of the current blocking layer and which are larger in area than the opening portion are formed. The active layer has a multiple quantum well structure constituted by a cyclic structure formed by cyclically stacking two types of InGaAlN layers which have different band gaps and are 10 nm or more thick.

Abstract: The invention provides a diffraction grating lens suitable for use as an objective lens for an optical disk recording/reproducing apparatus. This lens includes a light transmissive substrate of which a refractive index is larger than 1, having one plane and the other plane, and a diffraction grating pattern having a lens effect and constituted by a plurality of diffraction gratings formed on one plane of the light transmissive substrate. The diffraction grating pattern is for focusing an incident light beam flux at a focal point provided on a side of the other plane of the light transmissive substrate and is formed so that a numerical aperture, calculated with the focal point as a peak point, becomes larger than 1.

Abstract: A wedge-like etching groove is formed so that stresses can be collected along a cleavage surface of a nitride based compound semiconductor, and end portions are separated from a substrate. With these operations, a light-emitting layer can form an excellent mirror by a natural cleavage. Further, by separating a portion of the end surfaces from the substrate, it is possible to suppress a deformation from the substrate and therefore, a deterioration due to the deformation can be prevented. Therefore, it is possible to provide a nitride based compound semiconductor light-emitting device which can form an excellent cleavage surface with a simple process.

Abstract: A semiconductor laser is formed from a gallium nitride-based compound semiconductor material, and has a double-heterostructure portion obtained by sandwiching an active layer between an n-type cladding layer and a p-type cladding layer on a sapphire substrate. The double-heterostructure portion is formed into a mesa shape on the sapphire substrate via a GaN buffer layer. The two sides of this mesa structure are buried with GaN current blocking layers.

Abstract: Disclosed is a long-life GaN-based semiconductor device which is achieved by reducing the operating voltage of the semiconductor device comprising a GaN-based or a ZnSe-based compound semiconductor formed on a sapphire substrate and by preventing the electromigration of metal atoms from an electrode into compound semiconductor layers. The operating voltage of the GaN-based or ZnSe-based semiconductor device formed on a sapphire substrate or a SiC substrate can be greatly reduced by employing a ZnO layer doped with a significant amount of Al as a material for forming ohmic contact to p- or n- compound semiconductor layers. The long-life GaN-based semiconductor device can be attained by preventing electromigration of atoms from a metallic electrode by use of ZnO layer. If a superlattice including the ZnO layer is employed as an optical guide layer or if the superlattice including the ZnO layer as an active layer, a long-life laser diode with a low operating voltage and a wide wavelength range can be obtained.

Abstract: At an n--n hetero-interface in a ZnSe-based or GaN-based multilayered semiconductor laser and light-emitting diode, an excessive voltage drop causing the operating voltage to increased is reduced, thereby lengthening the service life of the device. A single or plurality of n-type intermediate layers are provided in the n--n hetero-interface region where the excessive voltage drop develops. The excessive voltage drop developing at the n--n hetero-interface is decreased by setting the energy value at the edge of the conduction band of each intermediate layer to a mid-value between the energy values at the edges of the conduction bands of the n-type compound semiconductors adjoining both sides of the intermediate layer. The configuration of a GaN-based MQW laser including the intermediate layer formed on sapphire substrate is shown.

Abstract: A semiconductor light-emitting device comprises a semiconductor light-emitting device section of a hexagonal type; and an electrically conductive semiconductor substrate of a cubic type combined into the semiconductor light-emitting device, and having an orientation of its cleavage facet conformed to an orientation of the cleavage facet of one of semiconductor layers forming the semiconductor light-emitting device section. The substrate of the cubic type is cleaved so that the semiconductor light-emitting device section of the hexagonal type is induced to be cleaved, and that a mirror surface can be easily formed.

Abstract: A light-emitting semiconductor device comprising an n-type cladding layer provided on a surface of a substrate and having concentric first and second parts, a first electrode mounted on the first part of the n-type cladding layer, a p-type cladding layer provided above the surface of the substrate and surrounding the first electrode and the second part of the n-type cladding layer, and a second electrode provided on the p-type cladding layer.

Abstract: A compound semiconductor device with an improved internal current blocking structure. The semiconductor device includes an n-clad layer of II-VI compound semiconductor, a p-clad layer of II-VI compound semiconductor, an active layer of II-VI compound semiconductor between the n-clad and p-clad layers, a very thin current blocking layer of n-type II-VI compound semiconductor on the p-clad layer and providing an opening, a p-contact layer of p-type II-VI compound semiconductor on the p-clad layer and the current blocking layer at the opening, and a p-side electrode on the p-contact layer.

Abstract: This invention provides a semiconductor light-emitting device including a semiconductor substrate consisting of a compound semiconductor of elements in the third and fifth groups of the period table, a first compound semiconductor layer formed directly on at least a portion of the semiconductor substrate and consisting of a compound semiconductor containing at least In and P, and a second compound semiconductor formed directly on the first compound semiconductor layer and consisting of a compound semiconductor of elements in the second and sixth groups of the periodic table. With this arrangement, it is possible to sufficiently prevent the occurrence of defects in the interface between the semiconductor substrate and the second compound semiconductor layer consisting of the compound semiconductor of the elements in the second and sixth groups of the periodic table.

Abstract: A semiconductor laser device includes a substrate, a first cladding layer formed on the substrate, an active layer formed on the first cladding layer, and a second cladding layer formed on the active layer having a conductivity type different from that of the first cladding layer, wherein at least one of the first and second cladding layers has a multiquantum barrier structure. The width of the first quantum barrier of the multiquantum barrier structure relative to the side of the active layer is 24 to 100 nm, the width of the second quantum barrier of the multiquantum barrier structure relative to the side of the active layer is 5 to 20 nm, and the multiquantum barrier structure is constituted by alternately stacking first thin layers consisting of In.sub.z (Ga.sub.1-x Al.sub.x).sub.1-z P (x is 0.7 to 1.0 and z is 0 to 1.0) and second thin layers consisting of In.sub.z (Ga.sub.1-y Al.sub.y).sub.1-z P (y is 0 to 0.3 and z is 0 to 1.0).

Abstract: According to the present invention, there is provided a semiconductor light-emitting device including a light-emitting layer having a first semiconductor layer, and formed on a main surface of one side of a semiconductor substrate, an upper-most layer of the light-emitting layer made of a compound semiconductor containing elements from the group II and group VI of the periodic table, the second semiconductor layer formed on the first semiconductor layer, and made of a material having a lattice constant different from that of the material of the semiconductor substrate by at least 2%, the second semiconductor layer having a film thickness of a critical film thickness, the first electrode formed on a main surface of the other side of the semiconductor substrate, and the second electrode formed on the second semiconductor layer.

Abstract: A wavelength converting optical device includes an optical waveguide which has a waveguide portion and a cladding portion, at least one of which is formed of a nonlinear optical material. A fundamental wave, incident on the waveguide portion from an input end face of the waveguide, is converted into an optical second harmonic wave by Cerenkov radiation and is radiated into the cladding portion. The radiated second harmonic wave is output from an output end face of the waveguide. A reflecting film is provided on the emerging end face of the waveguide. The reflecting film includes a high reflectivity with respect to the fundamental wave of a guide mode and a low reflectivity with respect to the optical second harmonic wave. A wave front converting element is arranged to oppose the reflecting film. The converting element has a diffraction grating for converting the second harmonic wave, emerging from the output end face of the waveguide, into a plane wave.

Abstract: According to this invention, a semiconductor laser device includes a compound semiconductor substrate, a double hetero structure formed on the compound semiconductor substrate and having an active layer and first and second cladding layers which interpose the active layer, a current blocking region formed in one facet portion of the double hetero structure in a resonator direction. A reflecting layer is arranged on the other facet of the double hetero structure in the resonator direction and has a reflectance higher than that of a natural cleavage surface, thereby shifting the oscillation wavelength of the laser device to a long wavelength side with respect to the wavelength of spontaneous radiation emitted from one facet of the double hetero structure.

Abstract: A semiconductor light-emitting element includes a semiconductor substrate of a first conductivity type, a lower cladding layer formed on the semiconductor substrate and constituted by an InGaAlP-based compound of the first conductivity type, an active layer formed on the lower cladding layer, and constituted by a material selected from the group consisting of GaAs, GaAlAs, and InGaAs, and an upper cladding layer formed on the active layer, and constituted by the InGaAlP-based compound of a second conductivity type, wherein the InGaAlP-based compound is represented by a formula In.sub.y (Ga.sub.1-x Al.sub.x).sub.y P, where x is in the range of 0.3 to 0.7 and y is in the range of 0.45 to 0.55.

Abstract: According to this invention, in a semiconductor laser, an n-type InGaAlP cladding layer, an InGaP active layer, and a p-type InGaAlP cladding layer are sequentially grown on an n-type GaAs substrate to form a double hetero structure. The active layer is constituted by an ordered structure having regularity in the <111> directions, and the p-type cladding layer is constituted by a disordered structure. Band discontinuity in conduction band between the active layer and the p-type cladding layer is increased to improve the temperature characteristics of the laser.

Abstract: A semiconductor laser device for radiating a laser beam from a double heterostructure section in which injected carriers having an energy source of the laser beam are confined consists of a compound semiconductor substrate with a prescribed lattice constant for loading the double heterostructure section, a lattice mismatched active layer with a first lattice constant which is 0.5% to 2.0% larger than the lattice constant of the substrate in the double heterostructure section for radiating the laser beam, a lattice mismatched cladding layer with a second lattice constant which is 0.2% to 2.0% smaller than the lattice constant of the substrate for confining the injected carriers in the active layer, and a cladding layer for confining the injected carriers in the active layer by co-operating with the lattice mismatched cladding layer.