Abstract: The invention provides a high-reliability nitride semiconductor laser that reduces the stress of a nitride dielectric film formed on a resonator's end face, thus reducing possible damage to the resonator's end face, which may occur during the formation of the nitride dielectric film. A method of manufacturing a nitride semiconductor laser according to the invention uses a nitride-based III-V compound semiconductor and includes the steps of (a) forming an adherence layer of a nitride dielectric on both a light-emitting and a light-reflecting end face of a resonator in plasma containing a nitrogen gas; and (b) forming a low-reflective and a high-reflective face-coating film of a dielectric on the adherence layers.

Abstract: A nitride semiconductor device with a p electrode having no resistance between itself and other electrodes, and a method of manufacturing the same are provided. A p electrode is formed of a first Pd film, a Ta film, and a second Pd film, and on a p-type contact layer of a nitride semiconductor. On the second Pd film, a pad electrode is formed. The second Pd film is formed on the entire upper surface of the Ta film which forms part of the p electrode, and serves as an antioxidant film that prevents oxidation of the Ta film. Preventing oxidation of the Ta film, the second Pd film can reduce the resistance that may exist between the p electrode and the pad electrode, thereby preventing a failure in contact between the p electrode and the pad electrode and providing the p electrode with low resistance.

Abstract: A semiconductor light emitting device has a gallium nitride compound semiconductor, and a first cladding layer of a first conductivity type, an active layer, an electron barrier layer of a second conductivity type and made of InxAlyGa1-x-yN (0?x?1 and 0?y?1), and a second cladding layer of the second conductivity type, laminated, in order, on a substrate. The electron barrier layer has a larger band gap than each of the active layer and the second cladding layer. The thickness of the electron barrier layer is in a range from 2 nm to 7 nm.

Abstract: A semiconductor light emitting device has an active layer of a gallium nitride compound semiconductor material, a first semiconductor layer of Inx1Aly1Ga1-x1-y1N (0?x1?1, 0?y1?1), on a p-layer side of the active layer, and which is subjected to tensile strain, a second semiconductor layer of Inx2Aly2Ga1-x2-y2N, wherein (0?x2?1, 0?y2?1), and which has a bandgap energy smaller than the bandgap energy of the first semiconductor layer, and a third semiconductor layer between the first semiconductor layer and the second semiconductor layer, of Inx3Aly3Ga1-x3-y3N, wherein (0?x3?1, 0?y3?1), and which has a bandgap energy smaller than the bandgap energy of the first semiconductor layer and larger than the bandgap energy of the second semiconductor layer.

Abstract: A semiconductor laser having a high electrostatic withstand voltage, resistant to a power supply surge, and having improved long-term reliability is obtained by reducing current leakage through a threading dislocation portion. The semiconductor laser includes a substrate having a high dislocation region having a dislocation density of 1×105 cm?2 or more, a crystalline semiconductors structure located on the substrate and having an active layer, an insulating film located on the semiconductors structure, a surface electrode located on the insulating film and electrically continuous with the semiconductor structure for injection of a current into the active layer, and a back electrode located on a rear surface of the substrate. The semiconductor laser has a laser resonator with a length L, and the area of the surface electrode is 120×L ?m2 or less.

Abstract: A semiconductor light emitting device including an active layer interposed between an n-type cladding layer and a p-type cladding layer employs an AlxGa1-xN (AlGaN) layer having an Al composition ratio x satisfying 0.01?x<0.06 as the n-type cladding layer. As the Al composition ratio x decreases below 0.06, the AlGaN layer increases in refractive index. Thus, the near field pattern (NFP) in the vertical direction can spread out, and full width at half maximum of FFP in the vertical direction can be minimized. Further, since lattice mismatch with a GaN substrate is reduced with decreasing Al composition ratio, the AlGaN layer can be thick without causing cracks or dislocations, and spreading of light into the GaN substrate can be minimized.

Abstract: A nitride semiconductor light-emitting device includes a p-type contact layer, a p-type intermediate layer below the p-type contact layer, and a p-type cladding layer below the p-type intermediate layer. Band gap energy differences between the p-type contact layer and the p-type intermediate layer and also between the p-type intermediate layer and the p-type cladding layer are, respectively, 200 meV or below.

Abstract: A semiconductor light-emitting diode includes an electrically conductive substrate transmissive to light-emitting wavelengths, and semiconductor layers including a light-emitting layer, on the substrate. A principal-surface electrode is located on the semiconductor layers and a rear-surface electrode having an opening is located on the rear surface of the substrate. The width of the opening is L, the distance between the rear-surface electrode and the light-emitting layer is t, L?2 t, and the rear-surface electrode covers no more than 40% of the rear surface of the substrata.

Abstract: A semiconductor light emitting device has a gallium nitride compound semiconductor, and a first cladding layer of a first conductivity type, an active layer, an electron barrier layer of a second conductivity type and made of InxAlyGa1-x-yN (0?x?1 and 0?y?1), and a second cladding layer of the second conductivity type, laminated, in orders, on a substrate. The electron barrier layer has a larger band gap than each of the active layer and the second cladding layer. The thickness of the electron barrier layer is in a range from 2 nm to 7 nm.

Abstract: In a semiconductor laser having an active layer of double-quantum-well structure that includes two InGaN well layers each of which has a thickness of 5 nm, a threshold current deteriorates to a relatively small degree while differential efficiency is improved considerably in a region having a light confinement coefficient ? of 3.0% or less. On the other hand, with the light confinement coefficient ? becoming less than 1.5%, the threshold current increases considerably while the amount of improvement in differential efficiency becomes small. It is therefore preferable that the lowest limit to the light confinement coefficient ? be about 1.5%. The differential efficiency of 1.6 W/A or more is obtained with the light confinement coefficient ? being 3.0% or less, and the differential efficiency of 1.7 W/A or more is obtained with the light confinement coefficient ? being 2.6% or less.

Abstract: A semiconductor light emitting device including an active layer interposed between an n-type cladding layer and a p-type cladding layer employs an AlxGa1-xN (AlGaN) layer having an Al composition ratio x satisfying 0.01?x<0.06 as the n-type cladding layer. As the Al composition ratio x decreases below 0.06, the AlGaN layer increases in refractive index. Thus, the near field pattern (NFP) in the vertical direction can spread out, and full width at half maximum of FFP in the vertical direction can be minimized. Further, since a lattice mismatch with a GaN substrate is reduced with decreasing Al composition ratio, the AlGaN layer can be formed thick without causing cracks or dislocation, and the spreading of light into the GaN substrate can be minimized.

Abstract: The present invention provides a semiconductor light-emitting device which exhibits small threshold current, high differential efficiency and good characteristics, by reducing electrons that overflow an electron barrier for trapping the electrons in an active layer. Of barrier layers that configure an active layer 20, a final barrier layer 1, which is a barrier layer closest to a p side, is made smaller in band gap than a barrier layer 2. Thus, as compared with a case where the barrier layer 1 is made of a material having the same band gap as that of the barrier layer 2, a band discontinuous amount (electron barrier) with an electron blocking layer 3 can be made larger. As a result, it is possible to reduce electrons that overflow the electron barrier.

Abstract: A ridge waveguide semiconductor laser that is excellent in optical output characteristic and high-frequency characteristic is provided. A p-type InP cladding layer having a ridge shape is formed over a p-type AlInAs cladding layer via a p-type InP layer and a p-type GaInAsP etching stopper layer, thereby suppressing the increase in the series resistance due to discontinuous band structure between an etching stopper layer and the AlGaInAs cladding layer and reducing the threshold current of the laser. Also the InP cladding layer is formed in a ridge shape with the portion near the base thereof being splayed like a skirt, thereby keeping the p-type metal electrode from the light emitting region and suppressing the absorption loss of light due to the p-type metal electrode.

Abstract: An optical modulator and a semiconductor laser device including the optical modulator, both reducing variations in the refractive index of an optical modulator or making variations negative without an increase in loss or a decrease in extinction ratio, as well as an optical communications system increasing an interval of distance at which modulated light is transmitted, by use of the optical modulator and the semiconductor laser device including the optical modulator. The optical modulator includes a semiconductor substrate of a first conductivity type; a light absorption layer on the semiconductor substrate and having a multiple quantum well structure, the multiple quantum well structure including a first well layer and second well layers. The peak wavelength of the absorption spectrum of the second well layers is shorter than the peak wavelength of the absorption spectrum of the first well layers A semiconductor cladding layer of the second conductivity type is on the light absorption layer.