Group III nitride crystal substrates and group III nitride crystal
Group III nitride crystal produced by cutting, from III nitride bulk crystal, a plurality of Group III nitride crystal substrates with major-surface plane orientation misoriented five degrees or less with respect to a crystal-geometrically equivalent plane orientation selected from the group consisting of {20-21}, {20-2-1}, {22-41}, and {22-4-1}, transversely arranging the substrates adjacent to each other such that their major surfaces are parallel to each other and such that their [0001] directions coincide with each other, and growing a Group III nitride crystal on the major surfaces. The Group III nitride crystal substrates are further characterized by satisfying at least either an oxygen-atom concentration of 1×10 16 cm −3 to 4×10 19 cm −3 or a silicon-atom concentration of 6×10 14 cm −3 to 5×10 18 cm −3 , and by having a carrier concentration of 1×10 16 cm −3 to 6×10 19 cm −3 .
1. A Group III nitride crystal substrate having a major surface with plane orientation being any one of [20-21], ([20-2-1], [22-41], and [22-4-1], the Group III nitride crystal substrate further characterized by:
satisfying at least one of either
an oxygen-atom concentration of between 5×10 16 cm −3 and 1×10 19 cm −3 inclusive, and
a silicon-atom concentration of between 6×10 14 cm −3 and 5×10 18 cm −3 inclusive;
having a carrier concentration of between (1×10 16 cm −3 ) and (6×10 19 cm −3 ) inclusive; and
in a cross-section through the crystal substrate perpendicular to either the <1-210> direction or to the <10-10> direction, an in-plane density of planar defects of from not fewer than 0.3 cm −1 to not more than 51 cm −1 .
2. A Group III nitride crystal substrate as recited in claim 1 , being of at least 10 cm 2 area.
3. A Group III nitride crystal substrate as recited in claim 1 , being of at least 40 cm 2 area.