Nitride structure and semiconductor device

A nitride structure, comprising:

• a first stacked body;
• a second stacked body;
• and
• an intermediate layer provided between the first stacked body and the second stacked body in a first direction and including Alz1Ga1-z1N (0≤z1≤1),
• the first stacked body including
• a plurality of first films including Alx1Ga1-x1N (0<x1≤1), and
• a plurality of second films including Alx2Ga1-x2N (0≤x2<1, x2<x1),
• one of the plurality of first films being provided between one of the plurality of second films and another one of the plurality of second films in the first direction,
• the one of the plurality of second films being provided between the one of the plurality of first films and another one of the plurality of first films in the first direction,
• the second stacked body including
• a plurality of third films including Alx3Ga1-x3N (0<x3≤1), and
• a plurality of fourth films including Alx4Ga1-x4N (0≤x4<1, x4<x3),
• one of the plurality of third films being provided between one of the plurality of fourth films and another one of the plurality of fourth films in the first direction,
• the one of the plurality of fourth films being provided between the one of the plurality of third films and another one of the plurality of third films in the first direction,
• the first stacked body including a plurality of pits,
• a part of the intermediate layer being provided in the plurality of pits, and
• the second stacked body not including the pits, or a second density of the pits in the second stacked body being lower than a first density of the plurality of pits in the first stacked body.