Semiconductor device including compound and nitride members

A semiconductor device, comprising:

• a first electrode;
• a second electrode;
• a third electrode, a position of the third electrode in a first direction being between a position of the first electrode in the first direction and a position of the second electrode in the first direction, the first direction being from the first electrode toward the second electrode;
• a semiconductor member including a first semiconductor region and a second semiconductor region,
• the first semiconductor region including Alx1Ga1-x1N (0≤x1<1), the first semiconductor region including a first partial region, a second partial region, a third partial region, a fourth partial region, and a fifth partial region, a second direction from the first partial region toward the first electrode crossing the first direction, a direction from the second partial region toward the second electrode being along the second direction, a direction from the third partial region toward the third electrode being along the second direction, a position of the fourth partial region in the first direction being between a position of the first partial region in the first direction and a position of the third partial region in the first direction, a position of the fifth partial region in the first direction being between the position of the third partial region in the first direction and a position of the second partial region in the first direction,
• the second semiconductor region including Alx2Ga1-x2N (0<x2≤1, x1<x2), the second semiconductor region including a first semiconductor portion and a second semiconductor portion;
• a first insulating member including silicon and oxygen, the first insulating member including a first insulating portion and a second insulating portion, the first semiconductor portion being between the fourth partial region and the first insulating portion, the second semiconductor portion being between the fifth partial region and the second insulating portion;
• a compound member including Alx3Ga1-x3N (0<x3≤1, x1<x3), the compound member including a first compound portion, a second compound portion, and a third compound portion;
• a nitride member including Alx4Ga1-x4N (0<x4≤1, x1<x4<x3) or Iny1Aly2Ga1-y1-y2N (0<y1≤1, 0≤y2<x3, y1+y2≤1), the nitride member including a first nitride portion, a second nitride portion, and a third nitride portion,
• the first compound portion being between the third partial region and the third electrode in the second direction, the first nitride portion being between the first compound portion and the third electrode in the second direction,
• the second compound portion being between the first semiconductor portion and the third electrode in the first direction, the second nitride portion being between the second compound portion and the third electrode in the first direction,
• the first semiconductor portion being between the fourth partial region and the third nitride portion,
• the third compound portion being between the first semiconductor portion and the third nitride portion,
• crystallinity of the first compound portion being higher than crystallinity of the third compound portion, crystallinity of the first nitride portion being higher than crystallinity of the third nitride portion;
• and
• a second insulating member including a first insulating region and a second insulating region, the first insulating region being between the first nitride portion and the third electrode in the second direction, the second insulating region being between the second nitride portion and the third electrode in the first direction.