Abstract: A semiconductor light-emitting device includes a substrate having a first energy bandgap, a first semiconductor layers on the substrate, an active layer on the first semiconductor layer, and a second semiconductor layer on the active layer. The active layer includes a quantum well layer, and a first barrier layer between the first semiconductor layer and the quantum well layer. The first semiconductor layer has a second energy bandgap wider than the first energy bandgap. The quantum well layer has a third energy bandgap narrower than the first and second energy bandgaps. The second semiconductor layer has a fourth energy bandgap wider than the third energy bandgap. The substrate has a refractive index greater than a refractive index of the first semiconductor layer. The refractive index of the first semiconductor layer is not less than a refractive index of the first barrier layer.

Abstract: A semiconductor light-emitting device includes a substrate having a first energy bandgap, a first semiconductor layers on the substrate, an active layer on the first semiconductor layer, and a second semiconductor layer on the active layer. The active layer includes a quantum well layer, and a first barrier layer between the first semiconductor layer and the quantum well layer. The first semiconductor layer has a second energy bandgap wider than the first energy bandgap. The quantum well layer has a third energy bandgap narrower than the first and second energy bandgaps. The second semiconductor layer has a fourth energy bandgap wider than the third energy bandgap. The substrate has a refractive index greater than a refractive index of the first semiconductor layer. The refractive index of the first semiconductor layer is not less than a refractive index of the first barrier layer.

Abstract: A semiconductor light-emitting device includes a semiconductor substrate and a light-emitting layer on the semiconductor substrate. The light-emitting layer includes at least one quantum well layer and barrier layers alternately stacked. The quantum well layer includes a first semiconductor mixed crystal having a larger lattice constant than a lattice constant of the semiconductor substrate. The barrier layers each includes a second semiconductor mixed crystal having a smaller lattice constant than the lattice constant of the semiconductor substrate. The quantum well layer includes a first strain amount that is a product of the layer thickness thereof and a first strain ratio. The barrier layer each includes a second strain amount that is a product of the layer thickness thereof and a second strain ratio. The quantum well layer and the barrier layers are provided such that the first strain amount is greater than the second strain amount.

Abstract: A semiconductor light-emitting device includes a GaAs (gallium arsenide) substrate of a cubic crystal, a light-emitting layer and a multi-semiconductor layer. The light-emitting layer being provided on the GaAs substrate. The light-emitting layer includes InGaAs (indium gallium arsenide) represented by a compositional formula InxGa1-xAs (0<x<1). The multi-semiconductor layer being provided on a front surface of the GaAs substrate between the GaAs substrate and the light-emitting layer. The multi-semiconductor layer is tilted with respect to a (100) plane of the cubic crystal. The multi-semiconductor layer includes a first layer and a second layer. The first and second layers are alternately stacked in a direction perpendicular to the front surface of the GaAs substrate. The first layer is different in composition from the second layer.

Abstract: A semiconductor device includes an n-type semiconductor layer; a first metal layer provided on the n-type semiconductor layer, the first metal layer including first atoms capable of being n-type impurities in the n-type semiconductor layer; a second metal layer provided on the first metal layer, the second metal layer including titanium atoms; a third metal layer provided on the second metal layer; and a second atom capable of being a p-type impurity in the n-type semiconductor layer. The second atom and a part of the titanium atoms are included in a vicinity of an interface between the first metal layer and the second metal layer.

Abstract: A semiconductor light-emitting device includes first and second semiconductor layers and a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer. The first semiconductor layer includes a compound semiconductor represented by a compositional formula AlXGa1-XAs (0<X<1). The first semiconductor layer has an n-type conductivity and includes a first impurity of the n-type. The first layer further includes carbon with a lower concentration than a concentration of the first impurity, and oxygen with a lower concentration than the concentration of the first impurity. The second semiconductor layer includes a compound semiconductor represented by a compositional formula AlYGa1-YAs (0<Y<1). The second semiconductor layer has a p-type conductivity and including a second impurity of the p-type. The second semiconductor layer further includes carbon with a concentration substantially equal to the carbon concentration in the first semiconductor layer.

Abstract: A semiconductor light-emitting device includes a substrate having a first energy bandgap, a first semiconductor layers on the substrate, an active layer on the first semiconductor layer, and a second semiconductor layer on the active layer. The active layer includes a quantum well layer, and a first barrier layer between the first semiconductor layer and the quantum well layer. The first semiconductor layer has a second energy bandgap wider than the first energy bandgap. The quantum well layer has a third energy bandgap narrower than the first and second energy bandgaps. The second semiconductor layer has a fourth energy bandgap wider than the third energy bandgap. The substrate has a refractive index greater than a refractive index of the first semiconductor layer. The refractive index of the first semiconductor layer is not less than a refractive index of the first barrier layer.

Abstract: A semiconductor light-emitting device includes a semiconductor substrate and a light-emitting layer on the semiconductor substrate. The light-emitting layer includes at least one quantum well layer and barrier layers alternately stacked. The quantum well layer includes a first semiconductor mixed crystal having a larger lattice constant than a lattice constant of the semiconductor substrate. The barrier layers each includes a second semiconductor mixed crystal having a smaller lattice constant than the lattice constant of the semiconductor substrate. The quantum well layer includes a first strain amount that is a product of the layer thickness thereof and a first strain ratio. The barrier layer each includes a second strain amount that is a product of the layer thickness thereof and a second strain ratio. The quantum well layer and the barrier layers are provided such that the first strain amount is greater than the second strain amount.

Abstract: A semiconductor light-emitting device includes first and second semiconductor layers and a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer. The first semiconductor layer includes a compound semiconductor represented by a compositional formula AlXGa1-XAs (0<X<1). The first semiconductor layer has an n-type conductivity and includes a first impurity of the n-type. The first layer further includes carbon with a lower concentration than a concentration of the first impurity, and oxygen with a lower concentration than the concentration of the first impurity. The second semiconductor layer includes a compound semiconductor represented by a compositional formula AlYGa1-YAs (0<Y<1). The second semiconductor layer has a p-type conductivity and including a second impurity of the p-type. The second semiconductor layer further includes carbon with a concentration substantially equal to the carbon concentration in the first semiconductor layer.

Abstract: A semiconductor device includes an n-type semiconductor layer; a first metal layer provided on the n-type semiconductor layer, the first metal layer including first atoms capable of being n-type impurities in the n-type semiconductor layer; a second metal layer provided on the first metal layer, the second metal layer including titanium atoms; a third metal layer provided on the second metal layer; and a second atom capable of being a p-type impurity in the n-type semiconductor layer. The second atom and a part of the titanium atoms are included in a vicinity of an interface between the first metal layer and the second metal layer.

Abstract: A semiconductor device includes an n-type semiconductor layer; a first metal layer provided on the n-type semiconductor layer, the first metal layer including first atoms capable of being n-type impurities in the n-type semiconductor layer; a second metal layer provided on the first metal layer, the second metal layer including titanium atoms; a third metal layer provided on the second metal layer; and a second atom capable of being a p-type impurity in the n-type semiconductor layer. The second atom and a part of the titanium atoms are included in a vicinity of an interface between the first metal layer and the second metal layer.

Abstract: Provided is a semiconductor device including: a group III-V semiconductor layer containing n-type impurities; a first conductive layer provided on the group III-V semiconductor layer, the first conductive layer containing titanium (Ti) and a first element that can be a p-type impurity of the group III-V semiconductor layer, the first conductive layer having a first region and a second region, a first element concentration of the second region being higher than that of the first region; and a second conductive layer provided on the first conductive layer.

Abstract: According to one embodiment, an optical semiconductor element includes a substrate, a light emitting layer, and a distributed Bragg reflector. The light emitting layer includes an AlGaAs multi quantum well layer. The distributed Bragg reflector is provided between the substrate and the light emitting layer. A pair of a first layer and a second layer is periodically stacked in the distributed Bragg reflector. The first layer includes AlxGa1-xAs. The second layer includes Inz(AlyGa1-y)1-zP. A refractive index n1 of the first layer is higher than a refractive index n2 of the second layer. The first layer has a thickness larger than ?0/(4n1) where ?0 is a center wavelength of a band on wavelength distribution of a reflectivity of the distributed Bragg reflector. The second layer has a thickness smaller than ?0/(4n2).

Abstract: According to one embodiment, a semiconductor light emitting device includes a substrate, and a multi quantum well layer provided on the substrate, and including a plurality of barrier layers sandwiched between three or more InGaAs well layers and two InGaAs well layers. The barrier layers include at least two regions having different mixed crystal ratios or at least two regions having different thicknesses.

Abstract: According to one embodiment, an optical semiconductor element includes a substrate, a light emitting layer, and a distributed Bragg reflector. The light emitting layer includes an AlGaAs multi quantum well layer. The distributed Bragg reflector is provided between the substrate and the light emitting layer. A pair of a first layer and a second layer is periodically stacked in the distributed Bragg reflector. The first layer includes AlxGa1-xAs. The second layer includes Inz(AlyGa1-y)1-zP. A refractive index n1 of the first layer is higher than a refractive index n2 of the second layer. The first layer has a thickness larger than ?0/(4n1) where ?0 is a center wavelength of a band on wavelength distribution of a reflectivity of the distributed Bragg reflector. The second layer has a thickness smaller than ?0/(4n2).

Abstract: According to one embodiment, a semiconductor light emitting device includes a substrate, and a multi quantum well layer provided on the substrate, and including a plurality of barrier layers sandwiched between three or more InGaAs well layers and two InGaAs well layers. The barrier layers include at least two regions having different mixed crystal ratios or at least two regions having different thicknesses.

Abstract: A semiconductor device includes an n-type semiconductor layer; a first metal layer provided on the n-type semiconductor layer, the first metal layer including first atoms capable of being n-type impurities in the n-type semiconductor layer; a second metal layer provided on the first metal layer, the second metal layer including titanium atoms; a third metal layer provided on the second metal layer; and a second atom capable of being a p-type impurity in the n-type semiconductor layer. The second atom and a part of the titanium atoms are included in a vicinity of an interface between the first metal layer and the second metal layer.

Abstract: According to one embodiment, a semiconductor device includes first and second electrodes, first, second, third, fourth, fifth, sixth and seventh semiconductor regions, and a gate electrode. The first semiconductor region is provided on the first electrode. The second semiconductor region is provided on a portion of the first semiconductor region. The third semiconductor region is provided on another portion of the first semiconductor region. The fourth semiconductor region is provided in at least a portion between the first and third semiconductor regions. The fifth semiconductor region is provided between the first and fourth semiconductor regions. The sixth semiconductor region is provided on the third semiconductor region. The seventh semiconductor region is provided selectively on the sixth semiconductor region. The gate electrode opposes the second, sixth, and seventh semiconductor regions. The second electrode is provided on the sixth and seventh semiconductor regions.

Abstract: A semiconductor device includes a semiconductor body, first and second electrodes, and a control electrode. The semiconductor body includes first to fourth semiconductor layers. The first electrode is provided on a front surface of the semiconductor body. The second electrode is provided on a back surface of the semiconductor body. The control electrode is provided between the semiconductor body and the first electrode. The second semiconductor layer is positioned between a portion and other portion of the first semiconductor layer in a first direction directed along the front surface. The third semiconductor layer contacts the portion of first semiconductor layer and the second semiconductor layer. The third semiconductor layer includes a first end portion positioned in the portion of the first semiconductor layer and a second end portion positioned in the second semiconductor layer. The fourth semiconductor layer is selectively provided in the second end portion.

Abstract: According to one embodiment, a semiconductor device includes first and second electrodes, first, second, third, fourth, fifth, sixth and seventh semiconductor regions, and a gate electrode. The first semiconductor region is provided on the first electrode. The second semiconductor region is provided on a portion of the first semiconductor region. The third semiconductor region is provided on another portion of the first semiconductor region. The fourth semiconductor region is provided in at least a portion between the first and third semiconductor regions. The fifth semiconductor region is provided between the first and fourth semiconductor regions. The sixth semiconductor region is provided on the third semiconductor region. The seventh semiconductor region is provided selectively on the sixth semiconductor region. The gate electrode opposes the second, sixth, and seventh semiconductor regions. The second electrode is provided on the sixth and seventh semiconductor regions.