Patent ID: 11970784
Assignee: SUMITOMO CHEMICAL COMPANY LIMITED
Field: Semiconductors (Electrical engineering)
Classification: CPC C  H | IPC C

Claim 15:
16. A laminated structure, comprising:
a base substrate comprising a single crystal of a group III nitride semiconductor and having a mirror main surface whose closest low index crystal plane is a (0001) plane;
an initial layer provided directly on the main surface of the base substrate and comprising a single crystal of a group III nitride semiconductor;
a first low oxygen concentration region provided on the initial layer and comprising a single crystal of a group III nitride semiconductor;
a high oxygen concentration region provided on the first low oxygen concentration region and comprising a single crystal of a group III nitride semiconductor; and
a second low oxygen concentration region provided on the high oxygen concentration region and comprising a single crystal of a group III nitride semiconductor,
wherein no mask layer is formed between the main surface of the base substrate and the initial layer, an oxygen concentration in the high oxygen concentration region is higher than an oxygen concentration in each of the initial layer, the first low oxygen concentration region, and the second low oxygen concentration region, and
when observing an arbitrary cross section perpendicular to the main surface,
a top surface of the first low oxygen concentration region has a plurality of valleys and a plurality of mountains,
an average distance between a pair of mountains separated in a direction along the entirety of the main surface is more than 100 the pair of mountains being closest to each other among the plurality of mountains that are upwardly convex inflection points where (0001) plane disappears, with one of the plurality of valleys sandwiched between them, and
a lowest index crystal plane closest to a surface of the second low oxygen concentration region is a (0001) plane over the entire surface of the second low oxygen concentration region.