According to one embodiment, a semiconductor device includes first, second, third nitride members, first, second, third electrodes, and a first insulating member. The first nitride member includes a first face along a first plane, a second face along the first plane, and a third face. The third face is connected with the first and second faces between the first and second faces. The third face crosses the first plane. The first face overlaps a part of the first nitride member. The second nitride member includes a first nitride region provided at the first face. The third nitride member includes a first nitride portion provided at the second face. The first electrode includes a first connecting portion. The second electrode includes a second connecting portion. The third electrode includes a first electrode portion. The first insulating member includes a first insulating region.

According to one embodiment, a semiconductor device includes first to third electrodes, a semiconductor member, a first conductive member, first and second insulating members, and a first nitride member. A position of the third electrode in a first direction from the first to second electrodes is between positions of the first and second electrodes in the first direction. The semiconductor member includes first and second semiconductor regions. The first semiconductor region includes first to fifth partial regions. The second semiconductor region includes first and second semiconductor portions. The second semiconductor portion includes first and second portions, and a third portion between the first and second portions. The first conductive member includes first and second conductive regions. The first insulating member includes a first insulating region. The second insulating member includes first and second insulating portions. The first nitride member includes a first nitride region.

According to one embodiment, a semiconductor device includes first to third electrodes, a semiconductor member, first and second insulating members, a compound member, and a nitride member. The third electrode is between the first and second electrodes. The semiconductor member includes first and second semiconductor regions. The first semiconductor region includes first to fifth partial regions. The second semiconductor region includes first and second semiconductor portions. The first insulating member includes first and second insulating portions. The first semiconductor portion is between the fourth partial region and the first insulating portion. The second semiconductor portion is between the fifth partial region and the second insulating portion. The compound member includes first to third compound portions. The nitride member includes first to third nitride portions. The second insulating member includes first and second insulating regions. The first and second insulating regions are between the nitride regions and the third electrode.

According to one embodiment, a semiconductor device includes first to third electrodes, first to third nitride regions, and first and second insulating films. The first nitride region includes Al.sub.x1Ga.sub.1−x1N, and includes first and second partial regions, a third partial region between the first and second partial regions, a fourth partial region between the first and third partial regions, and a fifth partial region between the third and second partial regions. The first nitride region includes first to fifth partial regions. The second nitride region includes Al.sub.x2Ga.sub.1−x2N, and sixth and seventh partial regions. At least a portion of the third electrode is between the sixth and seventh partial regions. The first insulating film includes silicon and oxygen and includes first and second insulating regions. The third nitride region includes Al.sub.x3Ga.sub.1−x3N, and first to seventh portions. The second insulating film includes silicon and oxygen and includes third to seventh insulating regions.

A semiconductor device includes a channel layer, a barrier layer disposed above the channel layer, a protective layer disposed on the barrier layer, and an insulating layer disposed on the protective layer. A composition of the barrier layer is represented by In.sub.x1Al.sub.x2Ga.sub.1-x1-x2N, where 0.00<=x1<=0.20, and 0.10<=x2<=1.00, and a composition of the protective layer is represented by In.sub.y1Al.sub.y2Ga.sub.1-y1-y2N, where 0.00<=y1<=0.20, and 0.10<=y2<=1.00, x2<y2. The protective layer is an amorphous layer.

A crystalline base substrate including a first semiconductor material and having a main surface is provided. The base substrate is processed so as to damage a lattice structure of the base substrate in a first region that extends to the main surface without damaging a lattice structure of the base substrate in second regions that are adjacent to the first region. A first semiconductor layer of a second semiconductor material is formed on a portion of the main surface that includes the first and second regions. A third region of the first semiconductor layer covers the first region of the base substrate, and a fourth region of the first semiconductor layer covers the second region of the base substrate. The third region has a crystalline structure that is disorganized relative to a crystalline structure of the fourth region. The first and second semiconductor materials have different coefficients of thermal expansion.

According to one embodiment, a semiconductor device includes first to third electrodes, first to third nitride regions, and first and second insulating films. The first nitride region includes Al.sub.x1Ga.sub.1−x1N, and includes first and second partial regions, a third partial region between the first and second partial regions, a fourth partial region between the first and third partial regions, and a fifth partial region between the third and second partial regions. The first nitride region includes first to fifth partial regions. The second nitride region includes Al.sub.x2Ga.sub.1−x2N, and sixth and seventh partial regions. At least a portion of the third electrode is between the sixth and seventh partial regions. The first insulating film includes silicon and oxygen and includes first and second insulating regions. The third nitride region includes Al.sub.x3Ga.sub.1−x3N, and first to seventh portions. The second insulating film includes silicon and oxygen and includes third to seventh insulating regions.

According to one embodiment, a semiconductor device includes first to third electrodes, first to third nitride regions, and first and second insulating films. The first nitride region includes Al.sub.x1Ga.sub.1−x1N, and includes first and second partial regions, a third partial region between the first and second partial regions, a fourth partial region between the first and third partial regions, and a fifth partial region between the third and second partial regions. The first nitride region includes first to fifth partial regions. The second nitride region includes Al.sub.x2Ga.sub.1−x2N, and sixth and seventh partial regions. At least a portion of the third electrode is between the sixth and seventh partial regions. The first insulating film includes silicon and oxygen and includes first and second insulating regions. The third nitride region includes Al.sub.x3Ga.sub.1−x3N, and first to seventh portions. The second insulating film includes silicon and oxygen and includes third to seventh insulating regions.

According to one embodiment, a semiconductor device includes first, second and third electrodes, first and second semiconductor layers, first and second insulating members, and a first member. The third electrode includes a first electrode portion. The first electrode portion is between the first and second electrodes. The first semiconductor layer includes first, second, third, fourth, and 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 regions. The first insulating member includes first and second insulating regions. The second insulating member includes first and second insulating portions. The first insulating portion is between the fourth partial region and the first insulating region. The second insulating portion is between the fifth partial region and the second insulating region. The second semiconductor layer includes first, second, and third semiconductor portions.

According to one embodiment, a semiconductor device includes first to third electrodes, first to third nitride regions, and first and second insulating films. The first nitride region includes Al.sub.x1Ga.sub.1-x1N, and includes first and second partial regions, a third partial region between the first and second partial regions, a fourth partial region between the first and third partial regions, and a fifth partial region between the third and second partial regions. The first nitride region includes first to fifth partial regions. The second nitride region includes Al.sub.x2Ga.sub.1-x2N, and sixth and seventh partial regions. At least a portion of the third electrode is between the sixth and seventh partial regions. The first insulating film includes silicon and oxygen and includes first and second insulating regions. The third nitride region includes Al.sub.x3Ga.sub.1-x3N, and first to seventh portions. The second insulating film includes silicon and oxygen and includes third to seventh insulating regions.