Nitride semiconductor with multiple nitride regions of different impurity concentrations, wafer, semiconductor device and method for manufacturing the same

A nitride semiconductor, comprising:

• a nitride member,
• the nitride member including:
• a first nitride region including Alx1Ga1-x1N (0<x≤1);
• a second nitride region including Alx2Ga1-x2N (0<x2<1, x2<x1), the second nitride region including carbon;
• a third nitride region, the second nitride region being between the first nitride region and the third nitride region, the third nitride region including Al, Ga, and N, the third nitride region not including carbon, alternatively a third carbon concentration in the third nitride region being lower than a second carbon concentration in the second nitride region,
• a fourth nitride region including Alx4Ga1-x4N (0≤x4<1), and
• a fifth nitride region including Alx5Ga1-x5N (0≤x5<1, x4<x5), wherein
• the third nitride region is between the first nitride region and the fifth nitride region,
• the fourth nitride region is between the third nitride region and the fifth nitride region,
• the fourth nitride region includes a first film region and a second film region,
• the first film region is between the third nitride region and the second film region,
• the first film region includes carbon, and
• the second film region does not include carbon, alternatively a carbon concentration in the second film region is lower than a carbon concentration in the first film region.

A semiconductor device, comprising:

• a nitride semiconductor;
• a first electrode;
• a second electrode;
• a third electrode;
• and
• an insulating member,
• the nitride semiconductor comprising:
• a nitride member,
• the nitride member including:
• a first nitride region including Alx1Ga1-xN (0<x1≤1);
• a second nitride region including Alx2Ga1-2xN (0<x2<1, x2<x1), the second nitride region including carbon;
• a third nitride region, the second nitride region being between the first nitride region and the third nitride region, the third nitride region including Al, Ga, and N, the third nitride region not including carbon, alternatively a third carbon concentration in the third nitride region being lower than a second carbon concentration in the second nitride region,
• a fourth nitride region including Alx4Ga1-x4N (0≤x4<1), and
• a fifth nitride region including Alx5Ga1-x5N (0≤x5<1, x4<x5),
• the third nitride region being between the first nitride region and the fifth nitride region, and
• the fourth nitride region being between the third nitride region and the fifth nitride region,
• a direction from the first electrode to the second electrode being along a second direction crossing a first direction from the first nitride region to second nitride region,
• a position of the third electrode in the second direction being between a position of the first electrode in the second direction and a position of the second electrode in the second direction,
• the fourth nitride region including a first partial region, a second partial region, a third partial region, a fourth partial region, and a fifth partial region,
• a direction from the first partial region to the first electrode being along the first direction,
• a direction from the second partial region to the second electrode being along the first direction,
• the third partial region being between the first partial region and the second partial region in the second direction, a direction from the third partial region to the third electrode being along the first direction,
• the fourth partial region being between the first partial region and the third partial region in the second direction,
• the fifth partial region being between the third partial region and the second partial region in the second direction,
• the fifth nitride region including a sixth partial region and a seventh partial region,
• a direction from the fourth partial region to the sixth partial region being along the first direction,
• a direction from the fifth partial region to the seventh partial region being along the first direction, and
• the insulating member being between the nitride member and the third electrode.