Abstract: A hologram recording medium including a substrate, a hologram recording layer that records an interference pattern formed by a first wavelength beam, a wavelength selecting reflection layer provided between the substrate and the hologram recording layer that reflects the first wavelength beam and transmits a second wavelength beam, a beam absorbing layer provided between the substrate and the wavelength selecting reflection layer that absorbs the first wavelength beam, and an information layer provided between the substrate and the light absorbing layer in which information is recorded and reproduced by the second wavelength beam, a second information layer provided between the substrate and the information layer and a second wavelength selecting reflection layer provided between the information layer and the second information layer that reflects the second wavelength beam and transmits a third wavelength beam.

Abstract: Noise caused by scattering of an information beam and a recording and reproducing reference beam within an optical information recording medium is reduced and reliability of recording and reproduction is enhanced A substrate 11, a hologram recording layer 15 that records an interference pattern formed by a first wavelength beam 2, a wavelength selecting reflection layer 14 provided between the substrate and the hologram recording layer that reflects the first wavelength beam 2 and transmits a second wavelength beam 3, a beam absorbing layer 13 provided between the substrate and the wavelength selecting reflection layer that absorbs the first wavelength beam, and an information layer 12 provided between the substrate and the light absorbing layer in which information is recorded and reproduced by the second wavelength beam are provided.

Abstract: A light emitting device includes an n-type semiconductor layer, an active layer for generating light, the active layer being in electrical contact with the n-type semiconductor layer. A p-type semiconductor layer is in electrical contact with the active layer, and a p-electrode is in electrical contact with the p-type semiconductor layer. The p-electrode includes a layer of silver. In a preferred embodiment of the present invention, the n-type semiconductor layer and the p-type semiconductor layer are constructed from group III nitride semiconducting materials. In one embodiment of the invention, the silver layer is sufficiently thin to be transparent. In other embodiments, the silver layer is thick enough to reflect most of the light incident thereon. A fixation layer may be provided. The fixation layer may be a dielectric or a conductor.

Abstract: A light emitting device includes an n-type semiconductor layer, an active layer for generating light, the active layer being in electrical contact with the n-type semiconductor layer. A p-type semiconductor layer is in electrical contact with the active layer, and a p-electrode is in electrical contact with the p-type semiconductor layer. The p-electrode includes a layer of silver. In a preferred embodiment of the present invention, the n-type semiconductor layer and the p-type semiconductor layer are constructed from group III nitride semiconducting materials. In one embodiment of the invention, the silver layer is sufficiently thin to be transparent. In other embodiments, the silver layer is thick enough to reflect most of the light incident thereon. A fixation layer may be provided. The fixation layer may be a dielectric or a conductor.

Abstract: A light emitting device is constructed on a substrate. The device includes an n-type semiconductor layer in contact with the substrate, an active layer for generating light, the active layer being in electrical contact with the n-type semiconductor layer. A p-type semiconductor layer is in electrical contact with the active layer, and a p-electrode is in electrical contact with the p-type semiconductor layer. The p-electrode includes a layer of silver in contact with the p-type semiconductor layer. A bonding layer is formed overlying the silver layer to make an electrical connection to the silver layer. The silver layer may be thin and transparent or thicker (greater than 20 nm) and reflective.

Abstract: The nitride semiconductor layer structure comprises a buffer layer and a composite layer on the buffer layer. The buffer layer is a layer of a low-temperature-deposited nitride semiconductor material that includes AlN. The composite layer is a layer of a single-crystal nitride semiconductor material that includes AlN. The composite layer includes a first sub-layer adjacent the buffer layer and a second sub-layer over the first sub-layer. The single-crystal nitride semiconductor material of the composite layer has a first AlN molar fraction in the first sub-layer and has a second AlN molar fraction in the second sub-layer. The second AlN molar fraction is greater than the first AlN molar fraction. The nitride semiconductor laser comprises a portion of the above-described nitride semiconductor layer structure, and additionally comprises an optical waveguide layer over the composite layer and an active layer over the optical waveguide layer.

Abstract: The nitride semiconductor layer structure comprises a buffer layer and a composite layer on the buffer layer. The buffer layer is a layer of a low-temperature-deposited nitride semiconductor material that includes AlN. The composite layer is a layer of a single-crystal nitride semiconductor material that includes AlN. The composite layer includes a first sub-layer adjacent the buffer layer and a second sub-layer over the first sub-layer. The single-crystal nitride semiconductor material of the composite layer has a first AlN molar fraction in the first sub-layer and has a second AlN molar fraction in the second sub-layer. The second AlN molar fraction is greater than the first AlN molar fraction. The nitride semiconductor laser comprises a portion of the above-described nitride semiconductor layer structure, and additionally comprises an optical waveguide layer over the composite layer and an active layer over the optical waveguide layer.

Abstract: A method for generating a photoresist pattern on top of an object that includes a layer of material that is opaque to light of a predetermined wavelength. The object is first covered with a layer of photoresist material. The layer of photoresist material is then irradiated with light of the predetermined wavelength from a position under the object such that the object casts a shadow into the layer of photoresist. The photoresist material is then developed to generate the photoresist pattern. The layer of photoresist material is irradiated from below the object by providing a reflecting surface below the object and a light source above the object. A mask is positioned between the object and the light source such that the mask casts a shadow that covers the object and a portion of the area surrounding the object.

Abstract: A nitride semiconductor device that comprises a first layer, a second layer and a buffer layer sandwiched between the first layer and the second layer. The second layer is a layer of a single-crystal nitride semiconductor material including AlN and has a thickness greater than the thickness at which cracks would form if the second layer were grown directly on the first layer. The buffer layer is a layer of a low-temperature-deposited nitride semiconductor material that includes AlN. Incorporating the nitride semiconductor device into a semiconductor laser diode enables the laser diode to generate coherent light having a far-field pattern that exhibits a single peak.

Abstract: The nitride semiconductor layer structure comprises a buffer layer and a composite layer on the buffer layer. The buffer layer is a layer of a low-temperature-deposited nitride semiconductor material that includes AlN. The composite layer is a layer of a single-crystal nitride semiconductor material that includes AlN. The composite layer includes a first sub-layer adjacent the buffer layer and a second sub-layer over the first sub-layer. The single-crystal nitride semiconductor material of the composite layer has a first AlN molar fraction in the first sub-layer and has a second AlN molar fraction in the second sub-layer. The second AlN molar fraction is greater than the first AlN molar fraction. The nitride semiconductor laser comprises a portion of the above-described nitride semiconductor layer structure, and additionally comprises an optical waveguide layer over the composite layer and an active layer over the optical waveguide layer.

Abstract: A method for generating a photoresist pattern on top of an object that includes a layer of material that is opaque to light of a predetermined wavelength. The object is first covered with a layer of photoresist material. The layer of photoresist material is then irradiated with light of the predetermined wavelength from a position under the object such that the object casts a shadow into the layer of photoresist. The photoresist material is then developed to generate the photoresist pattern. The layer of photoresist material is irradiated from below the object by providing a reflecting surface below the object and a light source above the object. A mask is positioned between the object and the light source such that the mask casts a shadow that covers the object and a portion of the area surrounding the object.

Abstract: A nitride semiconductor device that comprises a first layer, a second layer and a buffer layer sandwiched between the first layer and the second layer. The second layer is a layer of a single-crystal nitride semiconductor material including AlN and has a thickness greater than the thickness at which cracks would form if the second layer were grown directly on the first layer. The buffer layer is a layer of a low-temperature-deposited nitride semiconductor material that includes AlN. Incorporating the nitride semiconductor device into a semiconductor laser diode enables the laser diode to generate coherent light having a far-field pattern that exhibits a single peak.

Abstract: A light emitting device is constructed on a substrate. The device includes an n-type semiconductor layer in contact with the substrate, an active layer for generating light, the active layer being in electrical contact with the n-type semiconductor layer. A p-type semiconductor layer is in electrical contact with the active layer, and a p-electrode is in electrical contact with the p-type semiconductor layer. The p-electrode includes a layer of silver in contact with the p-type semiconductor layer. A bonding layer is formed overlying the silver layer to make an electrical connection to the silver layer. The silver layer may be thin and transparent or thicker (greater than 20 nm) and reflective.

Abstract: A device with a low resistance zone having confinement, superior reproducibility, and a very high yield comprises a plurality of semiconductor layers, wherein layer resistivity is changed by annealing. The semiconductor layers include a resistance zone having a high activation coefficient of acceptor impurities and a resistance region having a low activation coefficient of acceptor impurities. The activation coefficient is controlled by irradiation with laser light. In addition, laser light is irradiated and absorbed into the semiconductor layers in one part of, or the entire, semiconductor layers, such that layer resistivity in the irradiated regions is changed by annealing resulting from such irradiation.

Abstract: A Group III-nitride semiconductor device that has a low voltage-drop p-contact and comprises a substrate layer, a metal electrode and an intermediate layer sandwiched between the substrate layer and the metal electrode. The substrate layer is a layer of a p-type Group III-nitride semiconductor, and the intermediate layer includes a Group III-nitride semiconductor in which atoms of a Group V element other than nitrogen have been substituted for a fraction of nitrogen atoms. The Group III-nitride semiconductor device is made by providing a substrate including a p-type Group III-nitride semiconductor having an exposed surface. Atoms of a Group V element other than nitrogen are substituted for a fraction of the nitrogen atoms of the p-type Group III-nitride semiconductor to form an intermediate layer extending into the p-type Group III-nitride semiconductor from the exposed surface. Metal is then deposited on the exposed surface to form an electrode in electrical contact with the intermediate layer.

Abstract: A light emitting device constructed on a substrate. The device includes an n-type semiconductor layer in contact with the substrate, an active layer for generating light, the active layer being in electrical contact with the n-type semiconductor layer. A p-type semiconductor layer is in electrical contact with the active layer, and a p-electrode is in electrical contact with the p-type semiconductor layer. The p-electrode includes a layer of silver in contact with the p-type semiconductor layer. In the preferred embodiment of the present invention, the n-type semiconductor layer and the p-type semiconductor layer are constructed from group III nitride semiconductor materials. In one embodiment of the invention, the silver layer is sufficiently thin to be transparent. In other embodiments, the silver layer is thick enough to reflect most of the light incident thereon. A fixation layer is preferably provided over the silver layer.

Abstract: A Group III-nitride semiconductor device that has a low voltage-drop p-contact and comprises a substrate layer, a metal electrode and an intermediate layer sandwiched between the substrate layer and the metal electrode. The substrate layer is a layer of a p-type Group III-nitride semiconductor, and the intermediate layer includes a Group III-nitride semiconductor in which atoms of a Group V element other than nitrogen have been substituted for a fraction of nitrogen atoms. The Group III-nitride semiconductor device is made by providing a substrate including a p-type Group III-nitride semiconductor having an exposed surface. Atoms of a Group V element other than nitrogen are substituted for a fraction of the nitrogen atoms of the p-type Group III-nitride semiconductor to form an intermediate layer extending into the p-type Group III-nitride semiconductor from the exposed surface. Metal is then deposited on the exposed surface to form an electrode in electrical contact with the intermediate layer.

Abstract: A buried reflector 50 in an epitaxial lateral growth layer forms a part of a light emitting device and allows for the fabrication of a semiconductor material that is substantially low in dislocation density. The laterally grown material is low in dislocation defect density where it is grown over the buried reflector making it suitable for high quality optical light emitting devices, and the embedded reflector eliminates the need for developing an additional reflector.

Abstract: An improved method for cleaning a group III-nitride-based semiconductor surface prior to depositing electrodes or growing additional layers of semiconductor. In a cleaning method according to the present invention, the surface of the semiconductor is brought into contact with an etchant solution that includes hydrofluoric acid. The etching step is preferably carried out at a HF concentration greater than 5% and at a temperature between 10 to 100.degree. C. in an inert atmosphere. The etchant solution may also include other acids. Group III-nitride semiconductor devices cleaned in this manner require lower driving voltages than devices cleaned with prior art methods.

Abstract: A gas-phase etchant is provided. The gas-phase etchant includes at least one halogen in gaseous form and/or at least one halogen halide in gaseous form. A Group III-nitride crystal is heated to a temperature in the range of 500.degree.-900.degree. C. and is etched in a flow of the gas-phase etchant. The gas-phase etchant may additionally include hydrogen. The gas-phase etchant may alternatively be diluted with inert gas, and the Group III-nitride crystal may be etched in a flow of the gas-phase etchant diluted with the inert gas.