Abstract: According to one embodiment, a nitride semiconductor includes a nitride member. The nitride member include a first nitride region, a second nitride region, and intermediate region. The first nitride region includes Alx1Ga1?x1N (0?x1<1). The Alx1Ga1?x1N includes a first element including at least one selected from the group consisting of Fe and Mn. The second nitride region includes Alx2Ga1?x2N (0?x2?1). A direction from the first nitride region to the second nitride region is along a first direction. The intermediate region is provided between the first nitride region and the second nitride region. The intermediate region includes Alz1Ga1?z1N (0?z1?1, x1<z1, x2<z1). The Alz1Ga1?z1N includes oxygen. A concentration of oxygen in the nitride member becomes maximum in the intermediate region.

Abstract: According to one embodiment, a semiconductor structure includes a substrate including silicon crystal, a first layer including AlN crystal, and an intermediate region provided between the silicon crystal and the AlN crystal. The intermediate region includes Al and nitrogen. A direction from the silicon crystal to the AlN crystal is along a first direction. A third lattice plane spacing in the first direction of a lattice of Al atoms in the intermediate region is longer than a first lattice plane spacing in the first direction of the silicon crystal and longer than a second lattice plane spacing in the first direction of the AlN crystal.

Abstract: According to one embodiment, a nitride semiconductor includes a nitride member. The nitride member includes a first nitride region including Alx1Ga1-x1N (0<x1?1), a second nitride region including Alx2Ga1-x2N (0<x2<1, x2<x1), and a third nitride region. The second nitride region is between the first nitride region and the third nitride region. The third nitride region includes Al, Ga, and N. The third nitride region does not include carbon, alternatively a third carbon concentration in the third nitride region is lower than a second carbon concentration in the second nitride region.

Abstract: According to one embodiment, a nitride semiconductor includes a nitride member. The nitride member includes a first nitride region including Alx1Ga1-x1N (0<x1?1), a second nitride region including Alx2Ga1-x2N (0<x2<1, x2<x1), and a third nitride region. The second nitride region is between the first nitride region and the third nitride region. The third nitride region includes Al, Ga, and N. The third nitride region does not include carbon, alternately a third carbon concentration in the third nitride region is lower than a second carbon concentration in the second nitride region.

Abstract: According to one embodiment, a semiconductor device includes a first electrode, a second electrode, a third electrode, a first semiconductor layer, a second semiconductor layer, and a first insulating layer. A position of the third electrode in a first direction is between a position of the first electrode in the first direction and a position of the second electrode in the first direction. The first semiconductor layer includes Alx1Ga1-x1N and includes a first partial region, a second partial region, and a third partial region. The second semiconductor layer includes Alx2Ga1-x2N. A portion of the second semiconductor layer is between the third partial region and the third electrode in the second direction. The first insulating layer includes a first insulating region. The first insulating region is between the third electrode and the portion of the second semiconductor layer in the second direction.

Abstract: According to one embodiment, a semiconductor device includes a substrate, and a first semiconductor layer including magnesium and Alx1Ga1?x1N. The first semiconductor layer includes first, second, and third regions. The first region is between the substrate and the third region. The second region is between the first and third regions. A first concentration of magnesium in the first region is greater than a third concentration of magnesium in the third region. A second concentration of magnesium in the second region decreases along a first orientation. The first orientation is from the substrate toward the first semiconductor layer. A second change rate of a logarithm of the second concentration with respect to a change of a position along the first orientation is greater than a third change rate of a logarithm of the third concentration with respect to the change of the position along the first orientation.

Abstract: A semiconductor device is provided, including: a substrate; and a first semiconductor layer including magnesium and Alx/Ga1?x1N (0?x1<1), the first semiconductor layer including a first region, a second region, and a third region, the first region being between the substrate and the third region, the second region being between the first region and the third region, a first concentration of magnesium in the first region being greater than a third concentration of magnesium in the third region, a second concentration of magnesium in the second region decreasing along a first orientation, the first orientation being from the substrate toward the first semiconductor layer, and the first region not including carbon, or a concentration of carbon in the first region being less than the concentration of carbon in the third region.

Abstract: According to one embodiment, a nitride semiconductor includes a nitride member. The nitride member includes a first nitride region including Alx1Ga1-x1N, a second nitride region including Alx2Ga1-x2N, and a third nitride region including Alx3Ga1-x3N. The second nitride region is provided between the first and third nitride regions in a first direction from the first nitride region to the second nitride region. The second nitride region includes carbon and oxygen. The first nitride region does not include carbon, or a second carbon concentration in the second nitride region is higher than a first carbon concentration in the first nitride region. The second carbon concentration is higher than a third carbon concentration in the third nitride region. A ratio of a second oxygen concentration in the second nitride region to the second carbon concentration is not less than 1.0 × 10-4 and not more than 1.4 × 10-3.

Abstract: According to one embodiment, a nitride semiconductor includes a nitride member. The nitride member includes a first nitride region including Alx1Ga1-×1N (0 < x1 ? 1), a second nitride region including Alx2Ga1-x2N (0 ? x2 < 1), and an intermediate region being between the first nitride region and the second nitride region. In a first direction from the first nitride region to the second nitride region, an oxygen concentration in the nitride member has a peak value at a first position included in the intermediate region. The peak value is 4.9 times or more a first oxygen concentration in the first nitride region. A second carbon concentration in the second nitride region is higher than a first carbon concentration in the first nitride region.

Abstract: A method for manufacturing a semiconductor device is provided, the method including forming an intermediate region including Alx3Ga1-x3N (0<x3?1 and x2<x3) on a first semiconductor layer including Alx1Ga1-x1N (0?x1<1); and forming a second semiconductor layer including Alx2In1-x2N (0<x2<1 and x1<x2) on the intermediate region, a first gas being used to form the intermediate region in the forming of the intermediate region, the first gas including a gas including Al, a gas including ammonia, and a gas including hydrogen, and a second gas being used to form the second semiconductor layer in the forming of the second semiconductor layer, the second gas including a gas including Al, a gas including In, a gas including ammonia, and a gas including nitrogen.

Abstract: According to one embodiment, a nitride crystal includes first, second, and third nitride crystal regions. The third nitride crystal region includes Al, and is provided between the first and second nitride crystal regions. A third oxygen concentration in the third nitride crystal region is greater than a first oxygen concentration in the first nitride crystal region and greater than a second oxygen concentration in the second nitride crystal region. A third carbon concentration in the third nitride crystal region is greater than a first carbon concentration in the first nitride crystal region and greater than a second carbon concentration in the second nitride crystal region. A <0001> direction of the first nitride crystal region is one of a first orientation from the second nitride crystal region toward the first nitride crystal region or a second orientation from the first nitride crystal region toward the second nitride crystal region.

Abstract: According to one embodiment, a semiconductor device includes first to third electrodes, first and second semiconductor regions, and a first member. The second electrode includes first and second electrode regions. A position of the third electrode is between a position of the first electrode and a position of the second electrode. The first semiconductor region includes first to fifth partial regions. The fourth partial region is between the first and third partial regions. The fifth partial region is between the third and second partial region. The second semiconductor region includes first to third semiconductor portions. At least a part of the third semiconductor portion is between the first semiconductor region and the second electrode region. The second semiconductor portion is between the first semiconductor portion and the third semiconductor region. The first member includes first and second regions.

Abstract: According to one embodiment, a semiconductor device includes a first crystal region, a second crystal region, a third crystal region, and a fourth crystal region. The first crystal region includes magnesium and Alx1Ga1-x1N (0?x1<1). The second crystal region includes Alx2Ga1-x2N (0<x2?1). The third crystal region is provided between the first crystal region and the second crystal region. The third crystal region includes oxygen and Alx3Ga1-x3N (0?x3?1 and x3<x2). The fourth crystal region is provided between the third crystal region and the second crystal region. The fourth crystal region includes Alx4Ga1-x4N (0?x4<1 and x4<x2).

Abstract: According to one embodiment, a wafer includes a silicon substrate including a first surface, and a nitride semiconductor layer provided on the first surface. The silicon substrate includes a plurality of first regions that can be distinguished from each other in an X-ray image of the wafer. The first regions are separated from an outer edge region of the silicon substrate. One of the first regions includes a plurality of first linear bodies along a first line direction. An other one of the first regions includes a plurality of second linear bodies along a second line direction. The second line direction crosses the first line direction.

Abstract: According to one embodiment, a nitride crystal includes first, second, and third nitride crystal regions. The third nitride crystal region includes Al, and is provided between the first and second nitride crystal regions. A third oxygen concentration in the third nitride crystal region is greater than a first oxygen concentration in the first nitride crystal region and greater than a second oxygen concentration in the second nitride crystal region. A third carbon concentration in the third nitride crystal region is greater than a first carbon concentration in the first nitride crystal region and greater than a second carbon concentration in the second nitride crystal region. A <0001> direction of the first nitride crystal region is one of a first orientation from the second nitride crystal region toward the first nitride crystal region or a second orientation from the first nitride crystal region toward the second nitride crystal region.

Abstract: According to one embodiment, a nitride semiconductor includes a base body including boron, a first nitride region including Alx1Ga1-x1N (0.98<x1?1), and a second nitride region including Alx2Ga1-x2N (0?x2<1, x2<x1). A concentration of boron in the base body is not less than 1×1019 cm?3. The first nitride region is between the base body and the second nitride region. The first nitride region includes a first surface facing the base body and a second surface facing the second nitride region. A second concentration of boron in the second surface is not more than 1/8000 of a first concentration of boron in the first surface.

Abstract: According to one embodiment, a semiconductor device includes a first electrode, a second electrode, a third electrode, a first semiconductor layer, a second semiconductor layer, and a first insulating layer. A position of the third electrode in a first direction is between a position of the first electrode in the first direction and a position of the second electrode in the first direction. The first semiconductor layer includes Alx1Ga1-x1N and includes a first partial region, a second partial region, and a third partial region. The second semiconductor layer includes Alx2Ga1-x2N. A portion of the second semiconductor layer is between the third partial region and the third electrode in the second direction. The first insulating layer includes a first insulating region. The first insulating region is between the third electrode and the portion of the second semiconductor layer in the second direction.

Abstract: According to one embodiment, a semiconductor device includes a first crystal region, a second crystal region, a third crystal region, and a fourth crystal region. The first crystal region includes magnesium and Alx1Ga1-x1N (0?x1<1). The second crystal region includes Alx2Ga1-x2N (0<x2?1). The third crystal region is provided between the first crystal region and the second crystal region. The third crystal region includes oxygen and Alx3Ga1-x3N (0?x3?1 and x3<x2). The fourth crystal region is provided between the third crystal region and the second crystal region. The fourth crystal region includes Alx4Ga1-x4N (0?x4<1 and x4<x2).

Abstract: According to one embodiment, a semiconductor device includes a substrate, and a first semiconductor layer including magnesium and Alx1Ga1?x1N. The first semiconductor layer includes first, second, and third regions. The first region is between the substrate and the third region. The second region is between the first and third regions. A first concentration of magnesium in the first region is greater than a third concentration of magnesium in the third region. A second concentration of magnesium in the second region decreases along a first orientation. The first orientation is from the substrate toward the first semiconductor layer. A second change rate of a logarithm of the second concentration with respect to a change of a position along the first orientation is greater than a third change rate of a logarithm of the third concentration with respect to the change of the position along the first orientation.

Abstract: According to one embodiment, a nitride semiconductor includes a base body, and a nitride member. The nitride member includes a first nitride region including Alx1Ga1-x1N (0<x1?1), and a second nitride region including Alx2Ga1-x2N (0?x2<1, x2<x1). The first nitride region is between the base body and the second nitride region. The first nitride region includes a first portion and a second portion. The second portion is between the first portion and the second nitride region. An oxygen concentration in the first portion is higher than an oxygen concentration in the second portion. The oxygen concentration in the second portion is not more than 1×1018/cm3. A first thickness of the first portion in a first direction from the first to second nitride regions is thinner than a second thickness of the second portion in the first direction.