Light emitting device and light emitting device package having same

• US 10,347,789 B2
• Filed: 11/11/2015
• Issued: 07/09/2019
• Est. Priority Date: 12/22/2014
• Status: Active Grant

• Current Assignee: Suzhou Lekin Semiconductor Company Limited
• Original Assignee: LG Innotek Company Limited (LG Corporation)
• Inventors: Kim, Chong Cook
• Primary Examiner(s): Gumedzoe, Peniel M
• Application Number:
  US15/538,435
• Publication Number:
  US 20170358705A1
• Time in Patent Office: 1,336 Days
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A light emitting device includes a first conductivity type semiconductor layer including a first conductivity type dopant, an active layer disposed on the first conductivity type semiconductor layer and including a plurality of barrier layers and a plurality of well layers, an electron blocking structure layer disposed on the active layer, and a second conductivity type semiconductor layer disposed on the electron blocking structure layer. The active layer includes a first barrier layer adjacent to the electron blocking structure layer and a first well layer adjacent to the first barrier layer. The plurality of barrier layers include a first conductivity type dopant. The electron blocking structure layer includes a plurality of semiconductor layers including a second conductivity type dopant and AlGaN-based semiconductor. The plurality of semiconductor layers include a first semiconductor layer having a first region adjacent to the first barrier layer. The first region of the first semiconductor layer includes AlGaN-based semiconductor having aluminum composition of 95% or more. A light emitting structure including the active layer and the electron blocking structure layer emits different peak wavelengths.

Claims

1. A light emitting device comprising:

a first conductivity type semiconductor layer comprising a first conductivity type dopant;

an active layer disposed on the first conductivity type semiconductor layer and comprising a plurality of barrier layers and a plurality of well layers;

an electron blocking structure layer disposed on the active layer;

a second conductivity type semiconductor layer disposed on the electron blocking structure layer and comprising a second conductivity type dopant;

a first electrode electrically connected to the first conductivity type semiconductor layer; and

a second electrode electrically connected to the second conductivity type semiconductor layer,

wherein the active layer comprises a first barrier layer adjacent to the electron blocking structure layer and a first well layer adjacent to the first barrier layer,

the plurality of barrier layers comprise a first conductivity type dopant,

the electron blocking structure layer comprises a plurality of semiconductor layers,

wherein the plurality of semiconductor layers include a second conductivity type dopant and AlGaN-based semiconductor,

the plurality of semiconductor layers comprise a first semiconductor layer having a first region adjacent to the first barrier layer,

the first region of the first semiconductor layer comprises AlGaN-based semiconductor having aluminum composition of 95% or more,

a light emitting structure comprising the active layer and the electron blocking structure layer emits different peak wavelengths, and

the electron blocking structure layer is disposed between the active layer and the second conductivity type semiconductor layer,

wherein the first barrier layer is disposed between the first semiconductor layer and the first well layer,

wherein a thickness of the first barrier layer is smaller than a thickness of the first well layer and is smaller than a thickness of another barrier layer within the plurality of barrier layers,

wherein the first well layer has a first band gap,

wherein the first barrier layer has a second band gap greater than the first band gap, and

wherein band gaps of at least two of the plurality of semiconductor layers within the electron blocking structure layer are greater than the second band gap.

2. The light emitting device according to claim 1, wherein the first conductivity type dopant comprises an n-type dopant,

the second conductivity type dopant comprises a p-type dopant,

wherein the different peak wavelengths include an ultraviolet light,

wherein the active layer emits a first peak wavelength, and

wherein the first peak wavelength is a shorter wavelength within the different peak wavelengths.

3. The light emitting device according to claim 2, wherein the plurality of semiconductor layers comprise a second semiconductor layer disposed between the first semiconductor layer and the second conductivity type semiconductor layer, and a third semiconductor layer disposed between the second semiconductor layer and the second conductivity type semiconductor layer, and

wherein aluminum composition of the second semiconductor layer is lower than aluminum composition of the first and third semiconductor layers.

4. The light emitting device according to claim 3, wherein the first semiconductor layer comprises a second region disposed between the first region and the second semiconductor layer,

the second region comprises AlGaN-based semiconductor, of which aluminum composition is lower than aluminum composition of the first region,

wherein the second semiconductor layer is formed in a well structure between the first and third semiconductor layer,

wherein the first region of the first semiconductor layer has a third band gap greater than the second band gap, and

wherein the second region of the first semiconductor layer has a fourth band gap smaller than the third band gap.

5. The light emitting device according to claim 4, wherein the aluminum composition of the AlGaN-based semiconductor in the second region is reduced linearly or stepwise from aluminum composition of AlGaN-based semiconductor in the first region.

6. The light emitting device according to claim 4, wherein a thickness of the second region is greater than a thickness of the first region.

7. The light emitting device according to claim 4, further comprising a third region disposed between the first region and the second region,

wherein aluminum composition of the third region is lower than aluminum composition of the first region and higher than aluminum composition of the second region.

8. The light emitting device according to claim 3, wherein the second semiconductor layer directly contacts the first semiconductor layer and the third semiconductor layer in a well structure, and

wherein the second semiconductor layer has a fifth band gap greater than the first band gap and smaller than a band gap of the first semiconductor layer.

9. The light emitting device according to claim 1, wherein a thickness of the first region is less than the thickness of the first well layer or is 50% or less of a thickness of the first semiconductor layer.

10. The light emitting device according to claim 1, wherein the well layer comprises AlGaN, and

the barrier layer comprises AlGaN, of which aluminum composition is higher than aluminum composition of the well layer.

11. The light emitting device according to claim 9,

wherein the first region of the first semiconductor layer has the widest band gap in the electron blocking structure layer and directly contacts the first barrier layer,

wherein average aluminum composition of the first semiconductor layer is 65% or more, and

wherein the thickness of the first semiconductor layer is in a range of 4.5 nm to 6 nm.

12. The light emitting device according to claim 4, wherein average aluminum composition of the first semiconductor layer is 65% or more, and

wherein the aluminum composition of the second region is in a range of 50% to 80%.

13. The light emitting device according to claim 4, wherein aluminum composition of the first semiconductor layer is gradually reduced in a direction far away from the active layer.

14. The light emitting device according to claim 4, wherein the active layer emits the first peak wavelength in a range of 270 nm to 290 nm,

wherein the electron blocking structure layer emits a second peak wavelength shorter than the first peak wavelength,

wherein the well layer includes an AlGaN,

wherein the barrier layer has an AlGaN which is a higher aluminum composition than an aluminum composition of the well layer.

15. The light emitting device according to claim 14, wherein the second peak wavelength is in a range of 260 nm to 270 nm.

16. The light emitting device according to claim 14, wherein the second peak wavelength is shorter than the first peak wavelength and has a difference from the first peak wavelength by 8 nm or more.

17. The light emitting device according to claim 1, further comprising a clad layer between the electron blocking structure layer and the second conductivity type semiconductor layer,

wherein each of the electron blocking structure layer, the second conductivity type semiconductor layer, and the clad layer comprise a p-type semiconductor layer.

18. A light emitting device package comprising:

a support member;

a light emitting device disposed on the support member; and

first and second electrode layers electrically connected to the light emitting device,

wherein a light emitting structure of the light emitting device emits ultraviolet light having different first and second peak wavelengths,

wherein the light emitting device includes;

a first conductivity type semiconductor layer comprising a first conductivity type dopant and electrically connected to the first electrode layer;

an active layer disposed on the first conductivity type semiconductor layer and comprising a plurality of barrier layers and a plurality of well layers;

an electron blocking structure layer disposed on the active layer; and

a second conductivity type semiconductor layer disposed on the electron blocking structure layer and electrically connected to the second electrode layer,

wherein the active layer comprises a first barrier layer adjacent to the electron blocking structure layer and a first well layer adjacent to the first barrier layer,

the plurality of barrier layers comprise a first conductivity type dopant,

the electron blocking structure layer comprises a plurality of semiconductor layers,

wherein the plurality of semiconductor layers include a second conductivity type dopant and AlGaN-based semiconductor,

the plurality of semiconductor layers comprise a first semiconductor layer having a first region adjacent to the first barrier layer,

the first region of the first semiconductor layer comprises AlGaN-based semiconductor having aluminum composition of 95% or more,

a light emitting structure comprising the active layer and the electron blocking structure layer emits different ultraviolet light,

wherein the first barrier layer is disposed between the first semiconductor layer and the first well layer,

wherein a thickness of the first barrier layer is smaller than a thickness of the first well layer and smaller than a thickness of another barrier layer within the plurality of barrier layers,

wherein the first well layer has a first band gap,

wherein the first barrier layer has a second band gap greater than the first band gap, and

wherein band gaps of at least two of the plurality of semiconductor layers within the electron blocking structure layer are greater than the second band gap.

19. The light emitting device package according to claim 18, wherein the active layer and the electron blocking structure layer of the light emitting structure emit the first peak wavelength in a range of 270 nm to 290 nm,

wherein the electron blocking structure layer comprises a second semiconductor layer disposed between the first semiconductor layer and the second conductivity type semiconductor layer, and a third semiconductor layer disposed between the second semiconductor layer and the second conductivity type semiconductor layer, and

wherein the first semiconductor layer has a second region between the first region and the second semiconductor layer,

wherein aluminum composition of the second semiconductor layer is lower than aluminum composition of the first and third semiconductor layers,

wherein the first region of the first semiconductor layer has a third band gap greater than the second band gap,

wherein the second region of the first semiconductor layer has a fourth band gap smaller than the third band gap,

wherein the second semiconductor layer has a fifth band gap smaller than the fourth band gap and greater than the first band gap, and

wherein the third semiconductor layer has a sixth band gap greater than the fifth band gap.

20. The light emitting device package according to claim 19,

wherein the electron blocking layer structure layer emits a second wavelength,

wherein the second wavelength is shorter than the first wavelength,

wherein the second peak wavelength is in a range of 260 nm to 270 nm, and has a difference from the first peak wavelength by 8 nm or more,

wherein the well layer includes an AlGaN layer,

wherein the barrier layer has an AlGaN layer which is a higher aluminum composition than an aluminum composition of the well layer,

the second region comprises AlGaN-based semiconductor, of which aluminum composition is lower than aluminum composition of the first region.