Semiconductor device

1. A semiconductor device, comprising:

a first electrode;

a second electrode;

a first nitride region including Al x1 Ga 1-x1 N (0≤x1<1), the first nitride region including a first partial region, a second partial region, a third partial region between the first partial region and the second partial region, a fourth partial region between the first partial region and the third partial region, and a fifth partial region between the third partial region and the second partial region, a first direction from the first partial region toward the first electrode crossing a second direction from the first electrode toward the second electrode, a third direction from the second partial region toward the second electrode being aligned with the first direction;

a second nitride region including Al x2 Ga 1-x2 N (0<x2≤1 and x1<x2), the second nitride region including a sixth partial region and a seventh partial region, a fourth direction from the fourth partial region toward the sixth partial region being aligned with the first direction, a fifth direction from the fifth partial region toward the seventh partial region being aligned with the first direction;

a third electrode, a sixth direction from the third partial region toward the third electrode being aligned with the first direction, at least a portion of the third electrode being between the sixth partial region and the seventh partial region in the second direction; and

a first insulating film including a first insulating region, the first insulating region being between the third partial region and the third electrode in the first direction,

the third partial region having a first surface opposing the first insulating region,

the fourth partial region having a second surface opposing the sixth partial region,

a ratio of a distance along the first direction between a position along the first direction of the first surface and a position along the first direction of the second surface to a length along the first direction of the sixth partial region being 2 or more,

a stacked region including the third partial region and the first insulating region and including a first position and a second position, the first position being between the second position and the third electrode in the first direction,

a first concentration of Na in the stacked region having a peak at the first position,

a second concentration of Na at the second position being 1/100 of the first concentration of Na at the first position,

a first distance along the first direction between the first position and the second position being 8 nm or less.

2. The device according to claim 1 , wherein the first distance is 5 nm or less.

3. The device according to claim 1 , wherein the ratio is 3 or more.

4. The device according to claim 1 , wherein the ratio is 3.5 or more.

5. The device according to claim 1 , further comprising a third nitride region including Al x3 Ga 1-x3 N (0<x3≤1 and x1<x3),

the third nitride region including first to seventh portions, the first portion being between the first insulating region and the third partial region, the second portion being between the third electrode and the fourth partial region, the third portion being between the third electrode and the fifth partial region, the fourth portion being between the third electrode and the sixth partial region, the fifth portion being between the third electrode and the seventh partial region, the sixth partial region being between the sixth portion and the fourth partial region, the seventh partial region being between the seventh portion and the fifth partial region.

6. The device according to claim 5 , further comprising a second insulating film including a second insulating region and a third insulating region,

the sixth partial region being between the fourth partial region and the second insulating region,

the seventh partial region being between the fifth partial region and the third insulating region.

7. The device according to claim 6 , wherein

the first insulating film further includes fourth to seventh insulating regions,

the fourth insulating region is between the fourth portion and the third electrode,

the fifth insulating region is between the fifth portion and the third electrode,

the sixth portion is between the sixth insulating region and the second insulating region, and

the seventh portion is between the seventh insulating region and the third insulating region.

8. The device according to claim 7 , wherein

the first insulating film further includes an eighth insulating region and a ninth insulating region,

the eighth insulating region is between the second portion and the third electrode, and

the ninth insulating region is between the third portion and the third electrode.

9. The device according to claim 6 , wherein

the first insulating film includes Na, silicon and oxygen, and

the second insulating film includes silicon and nitrogen.

10. The device according to claim 6 , wherein a crystallinity of the first portion is higher than a crystallinity of the sixth portion.

11. The device according to claim 6 , wherein

at least a portion of the first portion includes a crystal, and

at least a portion of the sixth portion is amorphous.

12. The device according to claim 6 , wherein a crystallinity of the second portion is higher than a crystallinity of the sixth portion.

13. The device according to claim 6 , wherein a crystallinity of the fourth portion is higher than a crystallinity of the sixth portion.

14. The device according to claim 6 , wherein

the first insulating film does not include nitrogen, or

a concentration of nitrogen included in the first insulating film is lower than a concentration of nitrogen included in the second insulating film.

15. The device according to claim 5 , wherein x3 is higher than x2.

16. The device according to claim 5 , wherein

x1 is not less than 0 and not more than 0.05,

x2 is not less than 0.1 and not more than 0.3, and

x3 is not less than 0.8 and not more than 1.