Nitride semiconductor light emitting device and fabrication method thereof

• US 8,222,654 B2
• Filed: 12/05/2005
• Issued: 07/17/2012
• Est. Priority Date: 12/23/2004
• Status: Expired due to Fees

• Current Assignee: LG Innotek Company Limited (LG Corporation)
• Original Assignee: LG Innotek Company Limited (LG Corporation)
• Inventors: Lee, Suk Hun
• Primary Examiner(s): Nguyen, Cuong Q
• Assistant Examiner(s): Gebreyesus, Yosef
• Application Number:
  US11/719,932
• Publication Number:
  US 20090166649A1
• Time in Patent Office: 2,416 Days
• Field of Search: 257/22, 257/94, 257/193, 257/200, 257/201, 257/E23.326, 257/E21.34, 257/E33.025, 257/E21.398, 257/E21.441, 257/E21.449, 257/E21.451, 257/E33.038, 257/E33.03, 257/E33.033, 257/E21.097, 257/E21.981, 257/9, 257/13, 257/14, 257/15, 257/17, 257/96, 257/97, 257/103, 257/E33.008, 257/E33.009, 257/E33.01, 257/E31.035, 257/E31.036, 257/E29.072, 257/E29.074, 257/E29.298, 438/11, 438/12, 438/14, 438/22, 438/48, 438/189, 438/190, 438/200, 438/46, 438/47, 438/44
• US Class Current: 257/94
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer

Abstract

The present invention relates to a nitride semiconductor light emitting device including: a substrate having a predetermined pattern formed on a surface thereof by an etch; a protruded portion disposed on a non-etched region of the substrate, and having a first buffer layer and a first nitride semiconductor layer stacked thereon; a second buffer layer formed on the etched region of the substrate; a second nitride semiconductor layer formed on the second buffer layer and the protruded portion; a third nitride semiconductor layer formed on the second nitride semiconductor layer; an active layer formed on the third nitride semiconductor layer to emit light; and a fourth nitride semiconductor layer formed on the active layer. According to the present invention, the optical extraction efficiency of the nitride semiconductor light emitting device can be enhanced.

Claims

1. A light emitting device comprising:

a substrate having a predetermined pattern on a surface thereof by an etch, wherein the predetermined pattern includes a plurality of etched regions and a plurality of non-etched regions;

a buffer layer on the substrate;

a first conductive semiconductor layer on the buffer layer, wherein the first conductive semiconductor layer includes an InGaN layer, an AlGaN layer, and a GaN layer, and wherein the AlGaN layer has a planar surface;

an active layer on the first conductive semiconductor layer; and

a second conductive semiconductor layer on the active layer,

wherein the plurality of non-etched regions are protruded from the plurality of etched regions,

wherein a lower-most portion of each non-etched region of the plurality of non-etched regions has a width greater than an upper-most portion of each non-etched region of the plurality of non-etched regions,

wherein the width of the lower-most portion of each non-etched region of the plurality of non-etched regions is in a range from 3 μ

m to 5 μ

m,

wherein a distance between side surfaces of two non-etched regions of the plurality of non-etched regions is greater than a depth of an etched region of the plurality of etched regions,

wherein a side surface of each non-etched region of the plurality of non-etched regions includes a convex surface,

wherein the second conductive semiconductor layer comprises a delta-doped layer, and

wherein the buffer layer completely covers the plurality of non-etched regions.

2. The light emitting device according to claim 1, wherein the substrate includes one of sapphire, silicon carbide, silicon, or GaAs.

3. The light emitting device according to claim 1, further comprising a contact layer on the second conductive semiconductor layer, and

wherein the first conductive semiconductor layer and the contact layer have a first conductivity and the second conductive semiconductor layer has a second conductivity, and

wherein the first conductivity and the second conductivity are different from each other.

4. The light emitting device according to claim 1, wherein the buffer layer includes one of a stack structure of AlInN/GaN, a super lattice structure of InGaN/GaN, a stack structure of In_xGa₁₋

xN/GaN, a stack structure of Al_xIn_yGa<sub>1−

(x+y)</sub>N/In_xGa<sub>1−

x</sub>N/GaN, an undoped GaN layer, or doped GaN layer.

5. The light emitting device according to claim 1, further comprising a transparent electrode on the second conductive semiconductor layer.

6. The light emitting device according to claim 1, wherein the second conductive semiconductor layer includes a super lattice structure.

7. The light emitting device according to claim 1, wherein a depth of each etched region of the plurality of etched regions is in a range of 0.3 μ

m to 1 μ

m.

8. A light emitting device comprising:

a substrate having a predetermined pattern on a surface thereof by an etch, wherein the predetermined pattern includes a plurality of etched regions and a plurality of non-etched regions;

a buffer layer on the substrate;

a first conductive semiconductor layer on the buffer layer, wherein the first conductive semiconductor layer includes an InGaN layer, an AlGaN layer, and a GaN layer, and wherein the AlGaN layer has a planar surface;

an active layer on the first conductive semiconductor layer; and

a second conductive semiconductor layer on the active layer,

wherein the plurality of non-etched regions are protruded from the plurality of etched regions,

wherein a lower-most portion of each non-etched region of the plurality of non-etched regions has a width greater than an upper-most portion of each non-etched region of the plurality of non-etched regions,

wherein a depth of the etched region is in a range of 0.3 μ

m to 1 μ

m,

wherein a distance between side surfaces of two non-etched regions of the plurality of non-etched regions is greater than a depth of an etched region of the plurality of etched regions,

wherein a side surface of each non-etched region of the plurality of non-etched regions includes a convex surface,

wherein the second semiconductor layer comprises a delta-doped layer, and

wherein the buffer layer completely covers the plurality of non-etched regions.

9. The light emitting device according to claim 8, wherein the substrate includes one of sapphire, silicon carbide, silicon, or GaAs.

10. The light emitting device according to claim 8, further comprising a contact layer on the second conductive semiconductor layer, and

wherein the first conductive semiconductor layer and the contact layer have a first conductivity and the second conductive semiconductor layer has a second conductivity.

11. The light emitting device according to claim 8, wherein the second conductive semiconductor layer includes a super lattice structure.

12. The light emitting device according to claim 8, wherein the InGaN layer has a content of an Indium of less than 5%.

13. The light emitting device according to claim 8, further comprising a transparent electrode on the second conductive semiconductor layer.

14. A light emitting device comprising:

a substrate having a predetermined pattern on a surface thereof by an etch, wherein the predetermined pattern includes a plurality of etched regions and a plurality of non-etched regions;

a buffer layer on the substrate;

a first conductive semiconductor layer on the buffer layer, wherein the first conductive semiconductor layer comprises an undoped GaN-based layer, a Si-doped GaN-based layer directly on the undoped GaN-based layer, and an InGaN layer directly on the Si-doped GaN-based layer, wherein the first conductive semiconductor layer further comprises an AlGaN layer, and wherein the AlGaN layer has a planar surface;

an active layer directly on the InGaN layer of the first conductive semiconductor layer, wherein the active layer comprises a single quantum well layer or a multi quantum well layer of In_xGa<sub>1−

x</sub>N/In_yGa<sub>1−

y</sub>N; and

a second conductive semiconductor layer on the active layer,

wherein the plurality of non-etched regions are protruded from the plurality of etched regions,

wherein a lower-most portion of each non-etched region of the plurality of non-etched regions has a width greater than an upper-most portion of each non-etched region of the plurality of non-etched regions,

wherein the second conductive semiconductor layer includes a super lattice structure,

wherein the second conductive semiconductor layer has a thickness of 500 Å

to 5000 Å

,

wherein a distance between side surfaces of two non-etched regions of the plurality of non-etched regions is greater than a depth of an etched region of the plurality of etched regions,

wherein a side surface of each non-etched region of the plurality of non-etched regions includes a convex surface.

15. The light emitting device according to claim 14, wherein the substrate includes one of sapphire, silicon carbide, silicon, or GaAs.

16. The light emitting device according to claim 14, further comprising a contact layer on the second conductive semiconductor layer, and

wherein the first conductive semiconductor layer and the contact layer have a first conductivity and the second conductive semiconductor layer has a second conductivity.

17. The light emitting device according to claim 14, wherein one period of the super lattice structure has a thickness less than 250 Å

.

18. The light emitting device according to claim 14, further comprising a transparent electrode on the second conductive semiconductor layer.

19. The light emitting device according to claim 14, wherein the first conductive semiconductor layer includes an Al-doped layer.

20. A light emitting device comprising:

a substrate having a predetermined pattern on a surface thereof by an etch, wherein the predetermined pattern includes a plurality of etched regions and a plurality of non-etched regions;

a buffer layer on the substrate;

a first conductive semiconductor layer on the buffer layer, wherein the first conductive semiconductor layer comprises an undoped GaN-based layer, a Si-doped GaN-based layer directly on the undoped GaN-based layer, and an InGaN layer directly on the Si-doped GaN-based layer, wherein the first conductive semiconductor layer further comprises an AlGaN layer, and wherein the AlGaN layer has a planar surface;

an active layer directly on the InGaN layer of the first conductive semiconductor layer;

a second conductive semiconductor layer on the active layer; and

a transparent electrode on the second conductive semiconductor layer,

wherein the plurality of non-etched regions are protruded from the plurality of etched regions,

wherein the plurality of non-etched regions includes a substantially flat top surface,

wherein the first conductive semiconductor layer includes an InGaN layer under the active layer,

wherein a depth of the etched region is in a range of 0.3 μ

m to 1 μ

m,

wherein a distance between side surfaces of two non-etched regions of the plurality of non-etched regions is greater than a depth of an etched region of the plurality of etched regions,

wherein a side surface of each non-etched region of the plurality of non-etched regions includes a convex surface, and

wherein the second conductive semiconductor layer comprises a delta-doped layer.

21. The light emitting device according to claim 20, wherein the substrate includes one of sapphire, silicon carbide, silicon, or GaAs.

22. The light emitting device according to claim 20, further comprising a contact layer on the second conductive semiconductor layer, and

wherein the first conductive semiconductor layer and the contact layer have a first conductivity and the second conductive semiconductor layer has a second conductivity.

23. The light emitting device according to claim 20, wherein the buffer layer includes one of a stack structure of AlInN/GaN, a super lattice structure of InGaN/GaN, a stack structure of In_xGa₁₋

xN/GaN, a stack structure of Al_xIn_yGa<sub>1−

(x+y)</sub>N/In_xGa<sub>1−

x</sub>N/GaN, an undoped GaN layer, or doped GaN layer.

24. The light emitting device according to claim 20, wherein the second conductive semiconductor layer includes a super lattice structure.

25. The light emitting device according to claim 20, wherein the plurality of etched regions includes a substantially flat top surface.

26. A light emitting device comprising:

a first conductive semiconductor layer having a first conductivity, wherein the first conductive semiconductor layer comprises an undoped GaN-based layer, a Si-doped GaN-based layer directly on the undoped GaN-based layer, and an InGaN layer directly on the Si-doped GaN-based layer, wherein the first conductive semiconductor layer further comprises an AlGaN layer, and wherein the AlGaN layer has a planar surface;

an active layer on the first conductive semiconductor layer;

a second conductive semiconductor layer having a second conductivity on the active layer; and

a contact layer having the first conductivity on the second conductive semiconductor layer,

wherein the contact layer has a thickness of less than 60 Å

,

wherein the contact layer has a substantially flat top surface,

wherein the first conductive semiconductor layer and the contact layer have a first conductivity and the second conductive semiconductor layer has a second conductivity, wherein the first conductivity and the second conductivity are different from each other, and

wherein the second conductive semiconductor layer comprises a delta-doped layer.

27. The light emitting device according to claim 26, wherein the second conductive semiconductor layer includes a super lattice structure.

28. The light emitting device according to claim 26, further comprising a substrate and a buffer layer under the first conductive semiconductor layer.

29. The light emitting device according to claim 26, wherein the substrate has a predetermined pattern on a surface thereof by an etch, and wherein the predetermined pattern includes a plurality of etched regions and a plurality of non-etched regions.

30. A light emitting device comprising:

a substrate having a predetermined pattern on a surface thereof, wherein a width of an upper portion of the pattern is narrower than a width of a lower portion of the pattern;

a first conductive semiconductor layer on the substrate, wherein the first conductive semiconductor layer comprises an InGaN layer and at least two GaN-based layers having different concentrations of Si from each other, wherein the at least two GaN-based layers comprise a first GaN-based layer and a second GaN-based layer, wherein the second GaN-based layer has a higher concentration of Si than the first GaN-based layer has, and wherein the InGaN layer is disposed directly on the second GaN-based layer, wherein the first conductive semiconductor layer further comprises an AlGaN layer, and wherein the AlGaN layer has a planar surface;

an active layer on the InGaN layer of the first conductive semiconductor layer, wherein the active layer comprises a single quantum well layer or a multi quantum well layer of In_xGa<sub>1−

x</sub>N/In_yGa<sub>1−

y</sub>N; and

a second conductive semiconductor layer on the active layer.

31. The light emitting device according to claim 30, wherein the first conductive semiconductor layer has a first conductivity and the second conductive semiconductor layer has a second conductivity, and wherein the first conductivity and the second conductivity are different from each other, and

wherein the light emitting device further comprises a contact layer having the first conductivity on the second conductive semiconductor layer.

32. The light emitting device according to claim 30, wherein the pattern is provided in a plurality.

33. The light emitting device according to claim 30, wherein the second conductive semiconductor layer includes a delta-doped layer having a thickness in a range of 500 Å

to 5000 Å

, and wherein the second conductive semiconductor layer includes an AlGaN layer doped with Mg.