Nitride semiconductor light-emitting element
A nitride semiconductor light-emitting element includes at least an n-type nitride semiconductor layer, a light-emitting layer, and a p-type nitride semiconductor layer. A multilayer body is provided between the n-type nitride semiconductor layer and the light-emitting layer, having at least one stack of first and second semiconductor layers. The second semiconductor layer has a greater band-gap energy than the first semiconductor layer. The first and second semiconductor layers each have a thickness of more than 10 nm and 30 nm or less. In applications in which luminous efficiency at room temperature is a high priority, the first semiconductor layer has a thickness of more than 10 nm and 30 nm or less, the second semiconductor layer has a thickness of more than 10 nm and 40 nm or less, and the light-emitting layer has V-shaped recesses in cross-sectional view.
1. A nitride semiconductor light-emitting element comprising:
an n-type nitride semiconductor layer;
a light-emitting layer;
a p-type nitride semiconductor layer; and
a multilayer body between the n-type nitride semiconductor layer and the light-emitting layer, the multilayer body including at least one stack of a first semiconductor layer and a second semiconductor layer, wherein
both of the first semiconductor layer and the second semiconductor layer are doped with n-type impurity,
the second semiconductor layer has a greater band-gap energy than the first semiconductor layer,
the first semiconductor layer has a thickness of more than 10 nm and 30 nm or less, and the second semiconductor layer has a thickness of more than 10 nm and 40 nm or less, and
the light-emitting layer includes a plurality of V-shaped recesses (V-pits) with sizes of 150 nm or more in a cross-sectional view as seen in a direction perpendicular to a direction in which the first semiconductor layer and the second semiconductor are stacked.
2. The nitride semiconductor light-emitting element according to claim 1 , wherein the V-shaped recesses (V-pits) reach the multilayer body at a bottom of a V-shape thereof.
3. The nitride semiconductor light-emitting element according to claim 1 , wherein the V-shaped recesses (V-pits) are present as a large number of scattered cavities in a plan view of a top portion of the light-emitting layer with a plane surface density of the V-shaped recesses (V-pits) being 1×10 8 /cm 2 or more.
4. The nitride semiconductor light-emitting element according to claim 1 , wherein the first semiconductor layer and the second semiconductor layer have equal n-type impurity concentrations.
5. The nitride semiconductor light-emitting element according to claim 1 , wherein:
an n-type buffer layer is provided between the multilayer body and the light-emitting layer; and
the n-type buffer layer between the multilayer body and the light-emitting layer is an Al x3 In y3 Ga 1-x3-y3 N (0≤x3<1 and 0≤y3<1) layer that contains an n-type impurity and is in contact with the light-emitting layer.
6. The nitride semiconductor light-emitting element according to claim 1 , wherein:
an n-type buffer layer is provided between the n-type nitride semiconductor layer and the multilayer body; and
the n-type buffer layer between the n-type nitride semiconductor layer and the multilayer body is an Al s4 In t4 Ga 1-s4-t4 N (0≤s4<1 and 0≤t4<1) layer that contains an n-type impurity and is in contact with the multilayer body.
7. The nitride semiconductor light-emitting element according to claim 6 , wherein the n-type buffer layer between the n-type nitride semiconductor layer and the multilayer body has an n-type impurity concentration equal to at least one of an n-type impurity concentration of the first semiconductor layer and an n-type impurity concentration of the second semiconductor layer.
8. The nitride semiconductor light-emitting element according to claim 6 , wherein the n-type buffer layer between the n-type nitride semiconductor layer and the multilayer body has an n-type impurity concentration less than an n-type impurity concentration of the n-type nitride semiconductor layer.
9. A nitride semiconductor light-emitting element comprising:
an n-type nitride semiconductor layer;
a light-emitting layer;
a p-type nitride semiconductor layer; and
a multilayer body between the n-type nitride semiconductor layer and the light-emitting layer, the multilayer body including at least one stack of a first semiconductor layer and a second semiconductor layer, wherein
an n-type impurity concentration of each of the first semiconductor layer and the second semiconductor layer in the multilayer body is 3×10 18 cm −3 or more and less than 1.1×10 19 cm −3 ,
the second semiconductor layer has a greater band-gap energy than the first semiconductor layer,
the first semiconductor layer has a thickness of more than 10 nm and 30 nm or less, and the second semiconductor layer has a thickness of more than 10 nm and 40 nm or less,
the thickness of the second semiconductor layer is not less than a thickness of any layer that constitutes the light-emitting layer, and
the light-emitting layer includes a plurality of V-shaped recesses (V-pits) in a cross-sectional view as seen in a direction perpendicular to a direction in which the first semiconductor layer and the second semiconductor are stacked.
10. The nitride semiconductor light-emitting element according to claim 9 , wherein the V-shaped recesses (V-pits) reach the multilayer body at a bottom of a V-shape thereof.
11. The nitride semiconductor light-emitting element according to claim 9 , wherein the V-shaped recesses (V-pits) are present as a large number of scattered cavities in a plan view of a top portion of the light-emitting layer with a plane surface density of the V-shaped recesses (V-pits) being 1×10 8 /cm 2 or more.
12. The nitride semiconductor light-emitting element according to claim 9 , wherein the first semiconductor layer and the second semiconductor layer have equal n-type impurity concentrations.
13. The nitride semiconductor light-emitting element according to claim 9 , wherein:
an n-type buffer layer is provided between the multilayer body and the light-emitting layer; and
the n-type buffer layer between the multilayer body and the light-emitting layer is an Al x3 In y3 Ga 1-x3-y3 N (0≤x3<1 and 0≤y3<1) layer that contains an n-type impurity and is in contact with the light-emitting layer.
14. The nitride semiconductor light-emitting element according to claim 9 , wherein:
an n-type buffer layer is provided between the n-type nitride semiconductor layer and the multilayer body; and
the n-type buffer layer between the n-type nitride semiconductor layer and the multilayer body is an Al s4 In t4 Ga 1-s4-t4 N (0≤s4<1 and 0≤t4<1) layer that contains an n-type impurity and is in contact with the multilayer body.
15. The nitride semiconductor light-emitting element according to claim 14 , wherein the n-type buffer layer between the n-type nitride semiconductor layer and the multilayer body has an n-type impurity concentration equal to at least one of an n-type impurity concentration of the first semiconductor layer and an n-type impurity concentration of the second semiconductor layer.
16. A nitride semiconductor light-emitting element comprising:
an n-type nitride semiconductor layer;
a light-emitting layer;
a p-type nitride semiconductor layer; and
a multilayer body between the n-type nitride semiconductor layer and the light-emitting layer, the multilayer body including three or more and seven or less of stacks of a first semiconductor layer and a second semiconductor layer,
an n-type impurity concentration of each of the first semiconductor layer and the second semiconductor layer in the multilayer body is 3×10 18 cm −3 or more and less than 1.1×10 19 cm −3 ,
the second semiconductor layer has a greater band-gap energy than the first semiconductor layer,
the first semiconductor layer has a thickness of more than 10 nm and 30 nm or less, and the second semiconductor layer has a thickness of more than 10 nm and 40 nm or less, and
the light-emitting layer includes a plurality of V-shaped recesses (V-pits) with sizes of 150 nm or more in a cross-sectional view as seen in a direction perpendicular to a direction in which the first semiconductor layer and the second semiconductor are stacked.
17. The nitride semiconductor light-emitting element according to claim 16 , wherein the V-shaped recesses (V-pits) reach the multilayer body at a bottom of a V-shape thereof.
18. The nitride semiconductor light-emitting element according to claim 16 , wherein the V-shaped recesses (V-pits) are present as a large number of scattered cavities in a plan view of a top portion of the light-emitting layer with a plane surface density of the V-shaped recesses (V-pits) being 1×10 8 /cm 2 or more.
19. The nitride semiconductor light-emitting element according to claim 16 , wherein the first semiconductor layer and the second semiconductor layer have equal n-type impurity concentrations.
20. The nitride semiconductor light-emitting element according to claim 16 , wherein:
an n-type buffer layer is provided between the multilayer body and the light-emitting layer; and
the n-type buffer layer between the multilayer body and the light-emitting layer is an Al x3 In y3 Ga 1-x3-y3 N (0≤x3<1 and 0≤y3<1) layer that contains an n-type impurity and is in contact with the light-emitting layer.
21. The nitride semiconductor light-emitting element according to claim 16 , wherein:
an n-type buffer layer is provided between the n-type nitride semiconductor layer and the multilayer body; and
the n-type buffer layer between the n-type nitride semiconductor layer and the multilayer body is an Al s4 In t4 Ga 1-s4-t4 N (0≤s4<1 and 0≤t4<1) layer that contains an n-type impurity and is in contact with the multilayer body.
22. The nitride semiconductor light-emitting element according to claim 21 , wherein the n-type buffer layer between the n-type nitride semiconductor layer and the multilayer body has an n-type impurity concentration equal to at least one of an n-type impurity concentration of the first semiconductor layer and an n-type impurity concentration of the second semiconductor layer.
23. A nitride semiconductor light-emitting element comprising:
an n-type nitride semiconductor layer;
a light-emitting layer;
a p-type nitride semiconductor layer; and
a multilayer body between the n-type nitride semiconductor layer and the light-emitting layer, the multilayer body including at least one stack of a first semiconductor layer and a second semiconductor layer, wherein
an n-type impurity concentration of each of the first semiconductor layer and the second semiconductor layer in the multilayer body is 3×10 18 cm −3 or more and less than 1.1×10 19 cm −3 ,
the first semiconductor layer contains Indium and the second semiconductor layer contains less Indium than the first semiconductor layer,
the first semiconductor layer has a thickness of more than 10 nm and 30 nm or less, and the second semiconductor layer has a thickness of more than 10 nm and 40 nm or less, and
the light-emitting layer includes a plurality of V-shaped recesses (V-pits) with sizes of 150 nm or more in a cross-sectional view as seen in a direction perpendicular to a direction in which the first semiconductor layer and the second semiconductor are stacked.
24. The nitride semiconductor light-emitting element according to claim 23 , wherein the V-shaped recesses (V-pits) reach the multilayer body at a bottom of a V-shape thereof.
25. The nitride semiconductor light-emitting element according to claim 23 , wherein the V-shaped recesses (V-pits) are present as a large number of scattered cavities in a plan view of a top portion of the light-emitting layer with a plane surface density of the V-shaped recesses (V-pits) being 1×10 8 /cm 2 or more.
26. The nitride semiconductor light-emitting element according to claim 23 , wherein the first semiconductor layer and the second semiconductor layer have equal n-type impurity concentrations.
27. The nitride semiconductor light-emitting element according to claim 23 , wherein:
an n-type buffer layer is provided between the multilayer body and the light-emitting layer; and
the n-type buffer layer between the multilayer body and the light-emitting layer is an Al x3 In y3 Ga 1-x3-y3 N (0≤x3<1 and 0≤y3<1) layer that contains an n-type impurity and is in contact with the light-emitting layer.
28. The nitride semiconductor light-emitting element according to claim 23 , wherein:
an n-type buffer layer is provided between the n-type nitride semiconductor layer and the multilayer body; and
the n-type buffer layer between the n-type nitride semiconductor layer and the multilayer body is an Al s4 In t4 Ga 1-s4-t4 N (0≤s4<1 and 0≤t4<1) layer that contains an n-type impurity and is in contact with the multilayer body.
29. The nitride semiconductor light-emitting element according to claim 28 , wherein the n-type buffer layer between the n-type nitride semiconductor layer and the multilayer body has an n-type impurity concentration equal to at least one of an n-type impurity concentration of the first semiconductor layer and an n-type impurity concentration of the second semiconductor layer.