Crystal producing apparatus, crystal producing method, substrate producing method, gallium nitride crystal, and gallium nitride substrate
AssigneeRicoh Company, Ltd.
InventorsSeiji Sarayama, Hirokazu Iwata
Life of this patent
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Abstract
A crystal producing apparatus includes a crystal forming unit and a crystal growing unit. The crystal forming unit forms a first gallium nitride (GaN) crystal by supplying nitride gas into melt mixture containing metal sodium (Na) and metal gallium (Ga). The first GaN crystal is sliced and polished to form GaN wafers. The crystal growing unit grows a second GaN crystal on a substrate formed by using a GaN wafer, by the hydride vapor phase epitaxy method, thus producing a bulked GaN crystal.
Claims19
A method for producing a group-III nitride crystal, the method comprising:
- (a) obtaining a first group-III nitride crystal, grown by a flux method utilizing a seed crystal at a first crystal-growth speed, and having a dislocation density equal to or less than 105 cm−2;
- (b) growing a second group-III nitride crystal in bulk at a second crystal-growth speed, by vapor phase epitaxy method on a principal surface of the first group-III nitride crystal having the dislocation density equal to or less than 105 cm−2,
- wherein the second crystal-growth speed is faster than the first crystal-growth speed,
- wherein the first group-III nitride crystal is in a columnar shape, in which a length in a c-axis direction is longer than a length in an a-axis direction, and
- wherein the principal surface of the first group-III nitride crystal on which the second group-III nitride crystal is grown is an a-plane.
A gallium nitride crystal in bulks comprising:
- a first gallium nitride crystal formed by a flux method utilizing a seed crystal, the first gallium nitride crystal having a dislocation density equal to or less than 105 cm31 −2;
- and
- a second gallium nitride crystal grown by vapor phase epitaxy, on an a-plane of the first gallium nitride crystal having the dislocation density equal to or less than 105 cm31 2,
- wherein the first gallium nitride crystal is in a columnar shape, in which a length in a c-axis direction is longer than a length in an a-axis direction.
A group-III nitride substrate formed by a process comprising:
- (a) obtaining, as a first group-III nitride wafer, a slice of a first group-III nitride crystal, grown by a flux method utilizing a seed crystal at a first crystal-growth speed, and having a dislocation density equal to or less than 105 cm−2;
- (b) growing a second group-III nitride crystal in bulk at a second crystal-growth speed, by vapor phase epitaxy method on a first principal surface of the first group-III nitride wafer obtained in (a) and having the dislocation density equal to or less than 105 cm−2;
- (c) slicing the second group-III nitride crystal formed in (b) to form a substrate having a second principal surface,
- wherein the second principal surface of the substrate formed in (c) is parallel to the first principal surface of the first group-III nitride wafer on which the second group-III nitride crystal is grown in (b), and
- wherein the first group-III nitride crystal is in a columnar shape, in which a length in a c-axis direction is longer than a length in an a-axis direction.
Dependencies are inferred from the claim text.