Led that has bounding silicon-doped regions on either side of a strain release layer

• US 8,994,064 B2
• Filed: 01/17/2014
• Issued: 03/31/2015
• Est. Priority Date: 09/03/2011
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Chen, Zhen, Fu, Yi
• Primary Examiner(s): Maldonado, Julio J
• Assistant Examiner(s): REIDA, MOLLY KAY
• Application Number:
  US14/158,440
• Publication Number:
  US 20140131658A1
• Time in Patent Office: 438 Days
• Field of Search: None
• US Class Current: 257/101
• CPC Class Codes: H01L 33/0025 comprising only AIIIBV compounds
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/325 characterised by the doping materials

Abstract

A strain release layer adjoining the active layer in a blue LED is bounded on the bottom by a first relatively-highly silicon-doped region and is also bounded on the top by a second relatively-highly silicon-doped region. The second relatively-highly silicon-doped region is a sublayer of the active layer of the LED. The first relatively-highly silicon-doped region is a sublayer of the N-type layer of the LED. The first relatively-highly silicon-doped region is also separated from the remainder of the N-type layer by an intervening sublayer that is only lightly doped with silicon. The silicon doping profile promotes current spreading and high output power (lumens/watt). The LED has a low reverse leakage current and a high ESD breakdown voltage. The strain release layer has a concentration of indium that is between 5×10¹⁹ atoms/cm³ and 5×10²⁰ atoms/cm³, and the first and second relatively-highly silicon-doped regions have silicon concentrations that exceed 1×10¹⁸ atoms/cm³.

Claims

1. A light emitting device comprising:

a p-type layer;

an active layer including a plurality of quantum well layers and a plurality of quantum barrier layers;

a strain release layer comprising a plurality of periods, wherein each period comprises a first layer of indium gallium nitride and a second layer of indium gallium nitride, the first layer of indium gallium nitride having a first indium concentration, the second layer of indium gallium nitride having a second indium concentration different than the first indium concentration, the strain release layer having a second silicon concentration;

an interface layer disposed between the active layer and the strain release layer, the interface layer having a first silicon concentration; and

an n-side layer including a first n-type sublayer having a third silicon concentration,

wherein

the strain release layer is disposed between the n-side layer and the interface layer,

the first n-type sublayer of the n-side layer is a first bounding silicon-doped region disposed under the strain release layer, the third silicon concentration higher than the second silicon concentration, and

the first silicon concentration is higher than a silicon concentration of the plurality of quantum well layers and the plurality of quantum barrier layers.

2. The light emitting device of claim 1, wherein the n-side layer further includes a second n-type sublayer having a fourth silicon concentration and a third n-type sublayer having a fifth silicon concentration, the first n-type sublayer disposed between the strain release layer and the second n-type sublayer, the second n-type sublayer disposed between the first n-type sublayer and the third n-type sublayer, and

the fourth silicon concentration is lower than the third silicon concentration and the fifth silicon concentration.

3. The light emitting device of claim 1, wherein the interface layer adjoins the strain release layer and the active layer.

4. The light emitting device of claim 1, wherein first n-type sublayer of the n-side layer is a portion of the n-side layer adjoining the strain release layer.

5. The light emitting device of claim 1, wherein the first silicon concentration is higher than 1×

10¹⁸ atoms/cm³, and the active layer has a silicon concentration lower than 1×

10¹⁸ atoms/cm³.

6. The light emitting device of claim 2, wherein the second n-type sublayer of the n-side layer is more than fifty nanometers thick, and the interface layer is less than fifty nanometers thick.

7. The light emitting device of claim 1, wherein the first layer of each period of the strain release layer is less than five nanometers thick, and the second layer of each period of the strain release layer is less than five nanometers thick.

8. The light emitting device of claim 1, wherein the interface layer includes a barrier layer.

9. The light emitting device of claim 8, wherein the barrier layer is a gallium nitride (GaN) layer.

10. The light emitting device of claim 1, wherein the interface layer includes a peak of silicon concentration.

11. The light emitting device of claim 1, wherein the strain release layer includes a peak of silicon concentration.

12. The light emitting device of claim 1, wherein the interface layer is a second bounding silicon-doped region disposed on the strain release layer, the first silicon concentration higher than the second silicon concentration.

13. The light emitting device of claim 1, wherein the first layer of indium gallium nitride comprises In_xGa_1-xN (0≦

x<

0.12), and the second layer of indium gallium nitride comprises In_yGa_1-yN (0≦

y<

0.12), where x≠

y.

14. The light emitting device of claim 1, wherein the first n-type sublayer of the n-side layer includes a peak of silicon concentration.

15. The light emitting device of claim 2, the fourth silicon concentration is at least 2×

10¹⁷ atoms/cm³.

16. The light emitting device of claim 2, further comprising a metal electrode electrically connected to the third n-type sublayer.

17. The light emitting device of claim 2, further comprising a metal electrode electrically connected to the first n-type sublayer.

18. A light emitting device comprising:

an n-side layer including a first n-type sublayer having a first silicon concentration;

a strain release layer formed on the first n-type sublayer of the n-side layer and having a second silicon concentration, the strain release layer comprising an indium gallium nitride having a first indium concentration;

an active layer formed on the strain release layer and including a plurality of quantum well layers of indium gallium nitride, the quantum well layers having a second indium concentration different than the first indium concentration, and a plurality of quantum barrier layers;

an interface region between the strain release layer and the active layer, the interface region having a third silicon concentration; and

a p-type layer formed on the active layer,

wherein

the first silicon concentration of the first n-type sublayer of the n-side layer is higher than the second silicon concentration of the strain release layer,

the third silicon concentration of the interface region is higher than the second silicon concentration of the strain release layer, and

the third silicon concentration of the interface region is higher than a silicon concentration of the plurality of quantum well layers and the plurality of quantum barrier layers.

19. The light emitting device of claim 18, wherein the n-side layer further includes a second n-type sublayer having a fourth silicon concentration and a third n-type sublayer having a fifth silicon concentration, the second n-type sublayer disposed between the first n-type sublayer and the third n-type sublayer, and

the fourth silicon concentration is lower than the first silicon concentration and the fifth silicon concentration.

20. The light emitting device of claim 18, wherein the third silicon concentration is higher than 1×

10¹⁸ atoms/cm³, and the active layer has a silicon concentration lower than 1×

10¹⁸ atoms/cm³.

21. The light emitting device of claim 19, wherein the second n-type sublayer of the n-side layer is more than fifty nanometers thick.

22. The light emitting device of claim 18, wherein the strain release layer comprising a plurality of periods, each period comprising a first layer of an indium gallium nitride and a second layer of indium gallium nitride, the first layer of indium gallium nitride having a first indium concentration, the second layer of indium gallium nitride having a second indium concentration different than the first indium concentration, and

the first layer of each period of the strain release layer is less than five nanometers thick, and the second layer of each period of the strain release layer is less than five nanometers thick.

23. The light emitting device of claim 18, wherein the interface region includes a barrier layer.

24. The light emitting device of claim 23, wherein the barrier layer is a gallium nitride (GaN) layer.

25. The light emitting device of claim 18, wherein the interface region is formed directly on the strain release layer.

26. The light emitting device of claim 18, wherein the strain release layer is formed directly on the first n-type sublayer of the n-side layer.

27. The light emitting device of claim 18, wherein the interface region includes a peak of silicon concentration.

28. The light emitting device of claim 18, wherein the strain release layer includes a peak of silicon concentration.

29. The light emitting device of claim 18, wherein the second indium concentration in the quantum well layer is larger than the first indium concentration in the strain release layer.

30. The light emitting device of claim 18, where the strain release layer comprising a plurality of periods, wherein each period comprises a first layer of an indium gallium nitride and a second layer of indium gallium nitride, the first layer of indium gallium nitride having a first indium concentration, the second layer of indium gallium nitride having a third indium concentration different than the first indium concentration;

and the first layer of indium gallium nitride comprises In_xGa_1-xN (0≦

x<

0.12), and the second layer of indium gallium nitride comprises In_yGa_1-yN (0≦

y<

0.12), where x≠

y.

31. The light emitting device of claim 18, wherein the first n-type sublayer of the n-side layer includes a peak of silicon concentration.

32. The light emitting device of claim 19, the fourth silicon concentration is at least 2×

10¹⁷ atoms/cm³.

33. The light emitting device of claim 19, further comprising a metal electrode electrically connected to the third n-type sublayer.

34. A light emitting device comprising:

an n-side layer including a first n-type sublayer having a first silicon concentration, a second n-type sublayer having a second silicon concentration and a third n-type sublayer having a third silicon concentration, the second n-type sublayer disposed between the first n-type sublayer and the third n-type sublayer, the second silicon concentration lower than the first silicon concentration and the third silicon concentration;

a strain release layer formed on the third n-type sublayer of the n-side layer and having a fourth silicon concentration, the strain release layer comprising a plurality of periods, wherein each period comprises a first layer of indium gallium nitride and a second layer of indium gallium nitride, the first layer of indium gallium nitride having a first indium concentration, the second layer of indium gallium nitride having a second indium concentration different than the first indium concentration;

an active layer formed on the strain release layer and including a plurality of quantum well layers and a plurality of quantum barrier layers, the active layer having a fifth silicon concentration lower than 1×

10¹⁸ atoms/cm³;

an interface region between the strain release layer and the active layer, the interface region including a barrier layer and having a sixth silicon concentration higher than 1×

10¹⁸ atoms/cm³; and

a p-type layer formed on the multiple quantum well active layer,

wherein

the third silicon concentration and the sixth silicon concentration are higher than the fourth silicon concentration,

the sixth silicon concentration is higher than the fifth silicon concentration, and

the interface region includes a peak of silicon concentration.

35. The light emitting device of claim 34, wherein the barrier layer is a gallium nitride (GaN) layer.

36. The light emitting device of claim 34, wherein the first layer of indium gallium nitride comprises In_xGa_1-xN (0≦

x<

0.12), and the second layer of indium gallium nitride comprises In_yGa_1-yN (0≦

y<

0.12), where x≠

y.

37. The light emitting device of claim 34, wherein the third n-type sublayer of the n-side layer includes a peak of silicon concentration.

38. The light emitting device of claim 34, the second silicon concentration is at least 2×

10¹⁷ atoms/cm³.