Semiconductor light emitting device and manufacturing method thereof
A semiconductor light emitting device can have stable electric characteristics and can emit light with high intensity from a substrate surface. The device can include a transparent substrate and a semiconductor layer on the substrate. The semiconductor layer can include a first conductive type semiconductor layer, a luminescent layer, a second conductive type semiconductor layer, and first and second electrodes disposed to make contact with the first and second conductive type semiconductor layers, respectively. The first conductive type semiconductor layer, the luminescent layer, and the second conductive type semiconductor layer can be laminated in order from the side adjacent the substrate. An end face of the semiconductor layer can include a first terrace provided in an end face of the first conductive type semiconductor layer in parallel with the substrate surface, and an inclined end face region provided nearer to the substrate than the first terrace. The first electrode disposed in the inclined end face region can reflect light emitted from the luminescent layer to the substrate.
1. A semiconductor light emitting device comprising:
a substrate having a surface; and
a semiconductor layer disposed on at least a part of the surface of the substrate,
wherein the semiconductor layer includes,
a first conductive type semiconductor layer,
a luminescent layer,
a second conductive type semiconductor layer, and
a first electrode and a second electrode each disposed so as to make contact with the first conductive type semiconductor layer and the second conductive type semiconductor layer, respectively, wherein the first conductive type semiconductor layer, the luminescent layer, and the second conductive type semiconductor layer are laminated in this order from the substrate,
wherein the substrate is transparent so as to pass emission light from the luminescent layer,
an end face of the semiconductor layer includes a first terrace provided in an end face of the first conductive type semiconductor layer and positioned in parallel with the surface of the substrate, and an inclined end face region provided nearer to the substrate than the first terrace, and the inclined end face region being inclined with respect to the surface of the substrate,
the first electrode is disposed in the inclined end face region and is reflective, and the first electrode reflects light emitted from the luminescent layer to the substrate.
2. The semiconductor light emitting device according to claim 1 , wherein:
the second electrode is disposed adjacent the second conductive type semiconductor layer; and
the first terrace is disposed in a region within 5 degrees with respect to a first line that extends parallel to the substrate from a point and passes through a center of the luminescent layer in a cross-sectional thickness direction, the region bounded by a second line extending from the point at an angle of 5 degrees with respect to the first line, the point defined by an intersection of the first line with a line extending from an end of the second electrode and perpendicular to the substrate.
3. The semiconductor light emitting device according to claim 1 , wherein
the first terrace is disposed in a range within 0.3 μm from the luminescent layer in the thickness direction.
4. The semiconductor light emitting device according to claim 1 , wherein
the first electrode is disposed so as to cover an area from a vicinity of a boundary between the first terrace and the inclined end face region to the whole inclined end face region.
5. The semiconductor light emitting device according to claim 1 , wherein
a width of the first terrace in a direction in parallel with the substrate is greater than or equal to 5 μm.
6. The semiconductor light emitting device according to claim 1 , wherein
an inclination angle of the inclined end face region is between 35 degrees and 50 degrees with respect to the surface of the substrate.
7. The semiconductor light emitting device according to claim 1 , wherein
at least one second terrace which is approximately in parallel with the surface of the substrate is disposed in the inclined end face region between the first terrace and the substrate.
8. The semiconductor light emitting device according to claim 7 , wherein:
the first conductive type semiconductor layer includes a layer with high impurity concentration; and
at least one of the second terraces is disposed in the layer with high impurity concentration.
9. The semiconductor light emitting device according to claim 1 , wherein
the end face of the semiconductor layer in a region from the surface of the second conductive type semiconductor layer to the first terrace is approximately vertical with respect to the surface of the substrate.
10. The semiconductor light emitting device according to claim 1 , wherein
the end face of the semiconductor layer in a region from the surface of the second conductive type semiconductor layer to the first terrace is inclined with respect to the surface of the substrate.
11. A semiconductor light emitting device comprising:
a substrate; and
a semiconductor layer disposed on at least a part of a surface of the substrate, wherein
the semiconductor layer includes,
a first conductive type semiconductor layer including an end face,
a luminescent layer,
a second conductive type semiconductor layer, and
a first electrode and a second electrode each disposed so as to make contact with the first conductive type semiconductor layer and the second conductive type semiconductor layer, respectively, wherein the first conductive type semiconductor layer, the luminescent layer, and the second conductive type semiconductor layer are laminated in this order from the substrate,
wherein the substrate is transparent so as to pass emission light from the luminescent layer,
the semiconductor layer is divided into a plurality of partitions by a partition groove, the partition groove including an end face,
the end face of the partition groove forms an end face of the semiconductor layer,
the end face of the first conductive type semiconductor layer includes an inclined end face region, the inclined end face region being inclined so as to reflect light emitted from the luminescent layer to the substrate,
the first electrode is disposed in the inclined end face region and is reflective, and
the end face of the first conductive type semiconductor layer is provided with a first terrace that is positioned in parallel with the surface of the substrate, and the inclined end face region is disposed nearer to the substrate than the first terrace.
12. The semiconductor light emitting device according to claim 11 , wherein:
the second electrode is disposed adjacent the second conductive type semiconductor layer; and
the first terrace is disposed in a region within 5 degrees with respect to a first line that extends parallel to the substrate from a point and which passes through a center of the luminescent layer in a cross-sectional thickness direction, the region bounded by a second line extending from the point at an angle of 5 degrees with respect to the first line, the point defined by an intersection of the first line with a line extending from an end of the second electrode and perpendicular to the substrate.
13. The semiconductor light emitting device according to claim 11 , wherein
the first terrace is disposed in a range within 0.3 μm from the luminescent layer in the thickness direction.
14. The semiconductor light emitting device according to claim 11 , wherein
the first electrode is disposed so as to cover an area from a vicinity of a boundary between the first terrace and the inclined end face region to the whole inclined end face region.
15. The semiconductor light emitting device according to claim 11 , wherein
a width of the first terrace in a direction in parallel with the substrate is greater than or equal to 5 μm.
16. The semiconductor light emitting device according to claim 11 , wherein
an inclination angle of the inclined end face region is between 35 degrees and 50 degrees with respect to the surface of the substrate.
17. The semiconductor light emitting device according to claim 11 , wherein
at least one second terrace which is approximately in parallel with the surface of the substrate is disposed in the inclined end face region between the first terrace and the substrate.
18. The semiconductor light emitting device according to claim 17 , wherein:
the first conductive type semiconductor layer includes a layer with high impurity concentration; and
at least one of the second terraces is disposed in the layer with high impurity concentration.
19. The semiconductor light emitting device according to claim 11 , wherein
the end face of the semiconductor layer in a region from the surface of the second conductive type semiconductor layer to the first terrace is approximately vertical with respect to the surface of the substrate.
20. The semiconductor light emitting device according to claim 11 , wherein
the end face of the semiconductor layer in a region from the surface of the second conductive type semiconductor layer to the first terrace is inclined with respect to the surface of the substrate.
21. The semiconductor light emitting device according to claim 11 , wherein
the partition groove has a depth such that the partition groove reaches the substrate, and
the partition groove includes an inclined end face region extending from the first terrace to a top face of the substrate.
22. The semiconductor light emitting device according to claim 11 , wherein
the partition groove has a depth such that the partition groove does not reach the substrate; and
the partition groove includes an inclined end face region extending from the first terrace to a bottom of the partition groove.
23. The semiconductor light emitting device according to claim 22 , wherein
the depth of the partition groove is greater than or equal to 70% of a distance from the first terrace to the substrate.
24. The semiconductor light emitting device according to claim 11 , wherein
a corner of one of the partitions divided by the partition groove is rounded.
25. The semiconductor light emitting device according to claim 24 , wherein
the radius of curvature of the rounded corner is 0.03 to 0.1 times the length of a shorter side of the one of the partitions.
26. The semiconductor light emitting device according to claim 11 , wherein
a region having a predetermined shape is provided at an intersection of the partition grooves and is spaced from the first electrode.
27. The semiconductor light emitting device according to claim 11 , wherein
an area of one of the partitions is 0.0036 mm 2 to 0.09 mm 2 .
28. The semiconductor light emitting device according to claim 11 , wherein
the inclined end face region of the first conductive type semiconductor layer has at least two different inclination angles.
29. The semiconductor light emitting device according to claim 2 , wherein the second line extends downward towards the substrate from the point.
30. The semiconductor light emitting device according to claim 12 , wherein the second line extends downward towards the substrate from the point.