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US-12622107-B2 - Light-emitting element

US12622107B2US 12622107 B2US12622107 B2US 12622107B2US-12622107-B2

Abstract

A light-emitting element includes: a semiconductor stack including: a first light-emitting unit comprising nitride semiconductors including a first n-side semiconductor layer, a first p-side semiconductor layer, and a first active layer disposed between the first n-side semiconductor layer and the first p-side semiconductor layer, a second light-emitting unit comprising nitride semiconductors including a second n-side semiconductor layer, a second p-side semiconductor layer, and a second active layer disposed between the second n-side semiconductor layer and the second p-side semiconductor layer, and a tunnel junction layer disposed between the first p-side semiconductor layer and the second n-side semiconductor layer; an n-side electrode electrically connected to the first n-side semiconductor layer; and a p-side electrode electrically connected to the second p-side semiconductor layer.

Inventors

  • Ryota FUNAKOSHI
  • Toshihiko KISHINO

Assignees

  • NICHIA CORPORATION

Dates

Publication Date
20260505
Application Date
20220303
Priority Date
20210318

Claims (14)

  1. 1 . A light-emitting element comprising: a semiconductor stack comprising: a first light-emitting unit comprising nitride semiconductors including a first n-side semiconductor layer, a first p-side semiconductor layer, and a first active layer disposed between the first n-side semiconductor layer and the first p-side semiconductor layer, a second light-emitting unit comprising nitride semiconductors including a second n-side semiconductor layer, a second p-side semiconductor layer, and a second active layer disposed between the second n-side semiconductor layer and the second p-side semiconductor layer, and a tunnel junction layer disposed between the first p-side semiconductor layer and the second n-side semiconductor layer; an n-side electrode electrically connected to the first n-side semiconductor layer; and a p-side electrode electrically connected to the second p-side semiconductor layer; wherein: the first n-side semiconductor layer comprises a first stack part of a first n-type impurity concentration having a multilayer structure in which first layers and second layers having a different lattice constant from that of the first layers are alternately stacked; the second n-side semiconductor layer comprises a second stack part of a second n-type impurity concentration having a multilayer structure in which third layers and fourth layers having a different lattice constant from that of the third layers are alternately stacked; the second n-type impurity concentration is higher than the first n-type impurity concentration; and a thickness of the second stack part is less than a thickness of the first stack part.
  2. 2 . The light-emitting element according to claim 1 wherein the first layers and the second layers are undoped layers.
  3. 3 . The light-emitting element according to claim 1 wherein the third layers and the fourth layers are doped with an n-type impurity.
  4. 4 . The light-emitting element according to claim 1 wherein the tunnel junction layer comprises a semiconductor layer of a third n-type impurity concentration which is higher than the second n-type impurity concentration.
  5. 5 . The light-emitting element according to claim 1 wherein the second n-type impurity concentration is higher than the p-type impurity concentration of the second stack part.
  6. 6 . The light-emitting element according to claim 1 wherein the p-type impurity concentration of the second stack part is higher than the p-type impurity concentration of the first stack part.
  7. 7 . The light-emitting element according to claim 1 , wherein: a thickness of the first stack part is in a range of 30 nm to 150 nm; and a thickness of the second stack part is in a range of 30 nm to 150 nm.
  8. 8 . The light-emitting element according to claim 1 , wherein: a thickness of the first stack part is in a range of 50 nm to 70 nm; and a thickness of the second stack part is in a range of 30 nm to 50 nm.
  9. 9 . The light-emitting element according to claim 4 , further comprising: an intermediate layer disposed between the tunnel junction layer and the second stack part; wherein: an n-type impurity concentration of the intermediate layer is lower than the third n-type impurity concentration.
  10. 10 . The light-emitting element according to claim 9 , wherein a thickness of the intermediate layer is in a range of 100 nm to 200 nm.
  11. 11 . The light-emitting element according to claim 1 wherein the first n-type impurity concentration is in a range of 1×10 17 /cm 3 to 1×10 19 /cm 3 .
  12. 12 . The light-emitting element according to claim 10 wherein the first n-type impurity concentration is in a range of 1×10 17 /cm 3 to 1×10 19 /cm 3 .
  13. 13 . The light-emitting element according to claim 11 wherein the second n-type impurity concentration is in a range of 3×10 17 /cm 3 to 1×10 20 /cm 3 .
  14. 14 . The light-emitting element according to claim 12 wherein the second n-type impurity concentration is in a range of 3×10 17 /cm 3 to 1×10 20 /cm 3 .

Description

TECHNICAL FIELD A certain embodiment of the present invention relates to a light-emitting element. BACKGROUND ART Japanese Patent Publication No. 2017-157667, for example, discloses a light-emitting element that includes a nitride semiconductor layer having a tunnel junction layer. PRIOR ART DOCUMENTS Patent Documents Patent Document 1 JP 2017-157667 A SUMMARY OF INVENTION Technical Problem It is desirable to reduce the forward voltage of such a light-emitting element. One object of a certain embodiment of the present invention is to provide a light-emitting element capable of reducing the forward voltage. Solution to Problem A light-emitting element according to one embodiment of the present invention includes: a semiconductor stack having a first light-emitting unit comprising nitride semiconductors including a first n-side semiconductor layer, a first p-side semiconductor layer, and a first active layer disposed between the first n-side semiconductor layer and the first p-side semiconductor layer, a second light-emitting unit comprising nitride semiconductors including a second n-side semiconductor layer, a second p-side semiconductor layer, and a second active layer disposed between the second n-side semiconductor layer and the second p-side semiconductor layer, and a tunnel junction layer disposed between the first p-side semiconductor layer and the second n-side semiconductor layer; an n-side electrode electrically connected to the first n-side semiconductor layer; and a p-side electrode electrically connected to the second A-side semiconductor layer, the first n-side semiconductor layer including a first stack part of a first n-type impurity concentration having a multilayer structure in which first layers and second layers having a different lattice constant from that of the first layers are alternately stacked, the second n-side semiconductor layer including a second stack part of a second n-type impurity concentration having a multilayer structure in which third layers and fourth layers having a different lattice constant from that of the third layers are alternately stacked, and the second n-type impurity concentration being higher than the first n-type impurity concentration. Effect of the Invention According to the light-emitting element of an embodiment of the present invention, a light-emitting element capable of reducing the forward voltage can be provided. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view of a light emitting element according to one embodiment of the present invention. FIG. 2 is a flowchart of a method of manufacturing a light emitting element according to one embodiment of the present invention. FIG. 3A is a schematic diagram showing a method of manufacturing a light emitting element according to one embodiment of the present invention. FIG. 3B is a schematic diagram showing the method of manufacturing a light emitting element according to the embodiment of the present invention. FIG. 3C is a schematic diagram showing the method of manufacturing a light emitting element according to the embodiment of the present invention. DETAILED DESCRIPTION A certain embodiment of a light-emitting element according to the present invention will be explained below. The drawings referenced in the explanation below are schematic representations of the present invention. As such, the scale, spacing, and positional relationship of the members might be exaggerated or partially omitted. The scale or spacing of the members might not match between a top view and a cross-sectional view. In the explanation below, moreover, the same designations and reference numerals represent the same members or those of similar quality for which a detailed explanation might be omitted as appropriate. FIG. 1 is a schematic cross-sectional view of a light-emitting element 1 according to one embodiment of the present invention. The light-emitting element 1 according to this embodiment has a semiconductor stack 100 which has a first light-emitting unit 11 comprising nitride semiconductors including a first n-side semiconductor layer 20, a first p-side semiconductor layer 40, and a first active layer 30 disposed between the first n-side semiconductor layer 20 and the first p-side semiconductor layer 40, a second light-emitting unit 12 located on the first light-emitting unit 11 and comprising nitride semiconductors including a second n-side semiconductor layer 60, a second p-side semiconductor layer 80, and a second active layer 70 disposed between the second p-side semiconductor layer 60 and the second n-side semiconductor layer 80, and a tunnel junction layer 50 disposed between the first p-side semiconductor layer 40 and the second n-side semiconductor layer 60. The light-emitting element 1 has an n-side electrode 91 electrically connected to the first n-side semiconductor layer 20 and a p-side electrode 92 electrically connected to the second p-side semiconductor layer 80. The material