Abstract: A nitride semiconductor device includes an active layer including a first nitride semiconductor layer and a second nitride semiconductor layer which are periodically stacked, the second nitride semiconductor layer having a different composition from a composition of the first nitride semiconductor layer. An energy at a lower edge of a conduction band in the first nitride semiconductor layer is lower than an energy at a lower edge of a conduction band in the second nitride semiconductor layer, and an energy at an upper edge of a valence band in the first nitride semiconductor layer is lower than an energy at an upper edge of a valence band in the second nitride semiconductor layer.

Abstract: The nitride semiconductor material according to the present invention includes a group III nitride semiconductor and a group IV nitride formed on the group III nitride semiconductor, where an interface between the group III nitride semiconductor and the group IV nitride has a regular atomic arrangement. Moreover, an arrangement of nitrogen atoms of the group IV nitride in the interface and an arrangement of group III atoms of the group III nitride semiconductor in the interface may be substantially identical.

Abstract: A nitride semiconductor device includes: a substrate having a principal surface; a first nitride semiconductor layer formed on the principal surface of the substrate and includes one or more convex portions whose side surfaces are vertical to the principal surface; and a second nitride semiconductor layer selectively grown on the side surfaces of the one or more convex portions of the first nitride semiconductor layer.

Abstract: A nitride semiconductor device includes an active layer including a first nitride semiconductor layer and a second nitride semiconductor layer which are periodically stacked, the second nitride semiconductor layer having a different composition from a composition of the first nitride semiconductor layer. An energy at a lower edge of a conduction band in the first nitride semiconductor layer is lower than an energy at a lower edge of a conduction band in the second nitride semiconductor layer, and an energy at an upper edge of a valence band in the first nitride semiconductor layer is lower than an energy at an upper edge of a valence band in the second nitride semiconductor layer.

Abstract: A nitride semiconductor light emitting device includes: an active layer formed of a first III-V nitride semiconductor, the active layer having opposite surfaces which face each other; an alloy crystal layer formed of InxAlyGa1-x-yN (0<x<1, 0<y<1, 0<x+y<1) on one of the opposite surfaces of the active layer, the alloy crystal layer having n-type conductivity; and an ohmic electrode formed to be in contact with the alloy crystal layer. A transparent electrode is provided on the other surface of the active layer. A p-side electrode is provided on a portion of the transparent electrode.

Abstract: A semiconductor device, which includes an active layer made of a first semiconductor layer formed on a substrate, is designed so that a first oxidized area made of an oxide layer is formed on the active layer.

Abstract: A p-type semiconductor includes a host material 100 which is a semiconductor, an acceptor element 110 and a localized band formation element 120. Here, the acceptor element 110 is doped to the host material 100 and has fewer valence electrons than valance electrons of at least one of the elements which compose the host material 100; the localized band formation element 120 is doped to the host material 100, is isovalent with at least one of the elements which compose the host material 100 and has smaller electronegativity than the electronegativity of the element(s), and forms the localized band which activates holes of an acceptor level.

Abstract: An optical module includes a substrate, a waveguide body disposed on the substrate and including an optical waveguide for propagating light, and a photodetector. A curved portion for radiating light propagating through the optical waveguide from the optical waveguide is provided in a part of the optical waveguide, and the photodetector receives light radiated by the curved portion.

Abstract: To provide an optical waveguide having an optical waveguide core enclosed with clads, which is independent of a polarization direction. In the optical waveguide, an optical waveguide core is enclosed with clads, and a sectional shape of the core in a direction crossing a light traveling direction is quasi-square, and a cross section of the core decreases from the light incoming end to the outgoing end in the light traveling direction.

Abstract: A fractionally spaced cross-polarization interference canceller, wherein a compensation signal is generated through an adaptive filter operating in a frequency that is an integer multiple of a transmission data frequency. The cross-polarization interference canceller includes a mechanism for generating an error signal used to control coefficients of the adaptive filter in the integer multiple frequency. The mechanism is realized, for example, by using a waveform generator generating an estimate of a baseband signal in the integer multiple frequency using a plurality of estimates of transmission data and coefficients determined by an impulse response of a transmission path.

Abstract: In a digital radio transmission system for transmitting independent dual data by using cross polarization, an interference canceller detects cross polarization interference either directly or indirectly. An interference compensating signal is generated and applied to the main signal to cancel the interference element. In a case where no interference element is present, deterioration of cross polarization discrimination from an interference cancelling circuit is prevented by first determining whether an interference element actually exists and applying the interference compensating signal only when it does exist. The interference compensating signal can be attenuated based on the value of interference element so as to prevent undo deterioration of the cross polarization discrimination when the interference element is minimal.