Light emitting device
The present disclosure provides a light-emitting device, comprising: a light-emitting stack; a first semiconductor layer on the light-emitting stack; a first electrode formed on the first semiconductor layer and comprising an inner segment, an outer segment, and a plurality of extending segments electrically connecting the inner segment with the outer segment.
1. An light-emitting device, comprising:
a light-emitting stack;
a first semiconductor layer on the light-emitting stack;
a first electrode formed on the first semiconductor layer and comprising an inner segment, an outer segment, and a plurality of extending segments electrically connecting the inner segment with the outer segment.
2. The light-emitting device of claim 1 , further comprising a second semiconductor layer between the first semiconductor layer and the first electrode, wherein the second semiconductor layer has a thickness less than a maximum thickness of the first semiconductor layer.
3. The light-emitting device of claim 2 , wherein the first electrode is directly in contact with the second semiconductor layer.
4. The light-emitting device of claim 3 , wherein the second semiconductor layer comprises a Group III-V semiconductor material devoid of Al.
5. The light-emitting device of claim 3 , wherein the outer segment of the first electrode is directly in contact with the second semiconductor layer.
6. The light-emitting device of claim 5 , wherein the second semiconductor layer has a doping concentration of a dopant not greater than 1×10 18 /cm 3 .
7. The light-emitting device of claim 2 , further comprising an ohmic contact layer between the second semiconductor layer and the first electrode.
8. The light-emitting device of claim 7 , wherein the second semiconductor layer and the ohmic contact layer each have a doping concentration, and a ratio of the doping concentration of the ohmic contact layer to the doping concentration of the second semiconductor layer is not less than 2.
9. The light-emitting device of claim 7 , wherein the first electrode is directly in contact with the first semiconductor layer.
10. The light-emitting device of claim 9 , wherein the outer segment of the first electrode is directly in contact with the first semiconductor layer.
11. The light-emitting device of claim 10 , wherein the inner segment of the first electrode is directly in contact with the ohmic contact layer.
12. The light-emitting device of claim 9 , wherein the light-emitting stack comprises a first-type conductivity semiconductor layer, a second-type conductivity semiconductor layer, and an active layer sandwiched between the first-type and second-type conductivity semiconductor layers, the first semiconductor layer is between the second-type conductivity semiconductor layer and the first electrode, and the first semiconductor layer and the second-type conductivity semiconductor layer each comprises a Group III-V semiconductor material comprising a content of Al, wherein the content of Al of the first semiconductor layer is less than the content of Al of the second-type conductivity semiconductor layer.
13. The light-emitting device of claim 9 , wherein the first semiconductor layer comprises (Al y Ga (1-y) ) 1-x In x P, wherein 0≤x≤1, 0≤y≤0.3 or Al z Ga (1-z) As, wherein 0≤z≤0.3.
14. The light-emitting device of claim 2 , wherein the second semiconductor layer comprises an outer edge, and the outer edge and a side wall of the first semiconductor layer are substantially coplanar.
15. The light-emitting device of claim 1 , further comprising a light-absorbing layer on the first semiconductor layer, wherein the first semiconductor layer has a side wall, and the light-absorbing layer covers the side wall.
16. The light-emitting device of claim 15 , further comprising a reflective layer under the light-emitting stack.
17. The light-emitting device of claim 16 , wherein in a cross-sectional view of the light-emitting device, the reflective layer is not vertically overlapped with the light-absorbing layer.
18. The light-emitting device of claim 15 , wherein the first electrode comprises metal or metal alloy.
19. The light-emitting device of claim 18 , wherein the light-absorbing layer comprises titanium (Ti), chromium (Cr), nickels (Ni), Au, or combinations thereof.
20. The light-emitting device of claim 15 , wherein the first semiconductor layer comprises a top surface comprising a first region and a second region, the light-absorbing layer is on the first region and does not cover the second region, and a part of the second region is roughened.