Gan-Based Semiconductor Light-Emitting Device, Light Illuminator, Image Display Planar Light Source Device, and Liquid Crystal Display Assembly

• US 20070284564A1
• Filed: 09/08/2006
• Published: 12/13/2007
• Est. Priority Date: 09/13/2005
• Status: Active Grant

• Current Assignee: Sony Semiconductor Solutions Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Okuyama, Hiroyuki, Biwa, Goshi
• Granted Patent: US 8,168,966 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 5/3086 doping of the active layer
• CPC Class Codes: H01S 5/309 doping of barrier layers that confine charge carriers in the laser structure, e.g. the barriers in a quantum well structure barriers in quantum wells per se H01S5/3407
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser
• CPC Class Codes: H04N 9/315 : Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

A GaN-based semiconductor light-emitting device includes (A) a first GaN-based compound semiconductor layer 13 having n-type conductivity, (B) an active layer 15 having a multi-quantum well structure including well layers and barrier layers for separating between the well layers, and (C) a second GaN-based compound semiconductor layer 17 having p-type conductivity. The well layers are disposed in the active layer 15 so as to satisfy the relation d₁<d₂ wherein d₁ is the well layer density on the first GaN-based compound semiconductor layer side in the active layer and d₂ is the well layer density on the second GaN-based compound semiconductor layer side.

Claims

1. A GaN-based semiconductor light-emitting device comprising:

(A) a first GaN-based compound semiconductor layer having n-type conductivity;

(B) an active layer having a multi-quantum well structure including well layers and barrier layers for separating between the well layers; and

(C) a second GaN-based compound semiconductor layer having p-type conductivity;

wherein the well layers are disposed in the active layer so as to satisfy the relation d₁<

d₂ wherein d₁ is the well layer density on the first GaN-based compound semiconductor layer side in the active layer and d₂ is the well layer density on the second GaN-based compound semiconductor layer side.

2. The GaN-based semiconductor light-emitting device according to claim 1, wherein the following relations are satisfied:

500 (nm)≦

λ

₂≦

550 (nm)
0≦

|λ

₂−

λ

₃|≦

5 (nm)

wherein λ

₂ (nm) is the emission wavelength of the active layer when an operating current density is 30 A/cm², and λ

₃ (nm) is the emission wavelength of the active layer when an operating current density is 300 A/cm².

3. The GaN-based semiconductor light-emitting device according to claim 1, wherein the following relations are satisfied:

500 (nm)≦

λ

₂≦

550 (nm)
0≦

|λ

₁−

λ

₂|≦

10 (nm)
0≦

|λ

₂−

λ

₃|≦

5 (nm)

wherein λ

₁ (nm) is the emission wavelength of the active layer when an operating current density is 1 A/cm², λ

₂ (nm) is the emission wavelength of the active layer when an operating current density is 30 A/cm², and λ

₃ (nm) is the emission wavelength of the active layer when an operating current density is 300 A/cm².

4. The GaN-based semiconductor light-emitting device according to claim 1, wherein the following relations are satisfied:

430 (nm)≦

λ

₂≦

480 (nm)
0≦

|λ

₂−

λ

₃|≦

2 (nm)

wherein λ

₂ (nm) is the emission wavelength of the active layer when an operating current density is 30 A/cm², and λ

₃ (nm) is the emission wavelength of the active layer when an operating current density is 300 A/cm².

5. The GaN-based semiconductor light-emitting device according to claim 1, wherein the following relations are satisfied:

430 (nm)≦

λ

₂≦

480 (nm)
0≦

|λ

₁−

λ

₂|≦

5 (nm)
0≦

|λ

₂−

λ

₃|≦

2 (nm)

wherein λ

₁ (nm) is the emission wavelength of the active layer when an operating current density is 1 A/cm², λ

₂ (nm) is the emission wavelength of the active layer when an operating current density is 30 A/cm², and λ

₃ (nm) is the emission wavelength of the active layer when an operating current density is 300 A/cm².

6. The GaN-based semiconductor light-emitting device according to claim 1, wherein when the total thickness of the active layer is t₀, the well layer density in an active layer first region ranging from the first GaN-based compound semiconductor layer-side interface to the thickness of (t₀/3) in the active layer is d₁, and the well layer density in an active layer second region ranging from the second GaN-based compound semiconductor layer-side interface to the thickness of (2t₀/3) in the active layer is d₂, the well layers are disposed in the active layer to satisfy the relation d₁<

d₂.

7. The GaN-based semiconductor light-emitting device according to claim 1, wherein when the total thickness of the active layer is t₀, the well layer density in an active layer first region ranging from the first GaN-based compound semiconductor layer-side interface to the thickness of (t₀/2) in the active layer is d₁, and the well layer density in an active layer second region ranging from the second GaN-based compound semiconductor layer-side interface to the thickness of (t₀/2) in the active layer is d₂, the well layers are disposed in the active layer to satisfy the relation d₁<

d₂.

8. The GaN-based semiconductor light-emitting device according to claim 1, wherein when the total thickness of the active layer is t₀, the well layer density in an active layer first region ranging from the first GaN-based compound semiconductor layer-side interface to the thickness of (2t₀/3) in the active layer is d₁, and the well layer density in an active layer second region ranging from the second GaN-based compound semiconductor layer-side interface to the thickness of (t₀/3) in the active layer is d₂, the well layers are disposed in the active layer to satisfy the relation d₁<

d₂.

9. The GaN-based semiconductor light-emitting device according to claim 1, wherein the well layers are disposed in the active layer to satisfy the relation 1.2≦

d₂/d₁≦

10.

10. The GaN-based semiconductor light-emitting device according to claim 1, wherein the thicknesses of the barrier layers change from the first GaN-based compound semiconductor layer side to the second GaN-based compound semiconductor layer side.

11. The GaN-based semiconductor light-emitting device according to claim 1, wherein the thicknesses of the barrier layers change in three steps or more from the first GaN-based compound semiconductor layer side to the second GaN-based compound semiconductor layer side.

12. The GaN-based semiconductor light-emitting device according to claim 1, wherein the thickness of the barrier layer nearest the second GaN-based compound semiconductor layer is 20 nm or less.

13. The GaN-based semiconductor light-emitting device according to claim 1, wherein the thickness of the barrier layer nearest the first GaN-based compound semiconductor layer is twice or more the thickness of the barrier layer nearest the second GaN-based compound semiconductor layer.

14. The GaN-based semiconductor light-emitting device according to claim 1, wherein the active layer contains indium atoms.

15. The GaN-based semiconductor light-emitting device according to claim 1, wherein the number of the well layers in the active layer is 4 or more.

16. The GaN-based semiconductor light-emitting device according to claim 1, further comprising:

(D) an underlying layer containing In atoms and formed between the first GaN-based compound semiconductor layer and the active layer; and

(E) a superlattice layer containing a p-type dopant and formed between the active layer and the second GaN-based compound semiconductor layer.

17. The GaN-based semiconductor light-emitting device according to claim 1, wherein the GaN-based compound semiconductor layers constituting the active layer are composed of an undoped GaN-based compound semiconductor, or the n-type impurity concentration of the GaN-based compound semiconductor layers constituting the active layer is less than 2×

10¹⁷/cm³.

18. The GaN-based semiconductor light-emitting device according to claim 1, wherein the length of the short side or the short diameter of the active layer is 0.1 mm or less.

19. The GaN-based semiconductor light-emitting device according to claim 1, wherein the length of the short side or the short diameter of the active layer is 0.03 mm or less.

20. A light illuminator comprising a GaN-based semiconductor light-emitting device and a color conversion material on which light emitted from the GaN-based semiconductor light-emitting device is incident and which emits light at a wavelength different from the wavelength of the light emitted from GaN-based semiconductor light-emitting device, the GaN-based semiconductor light-emitting device including:

(A) a first GaN-based compound semiconductor layer having n-type conductivity;

(B) an active layer having a multi-quantum well structure including well layers and barrier layers for separating between the well layers; and

(C) a second GaN-based compound semiconductor layer having p-type conductivity;

wherein the well layers are disposed in the active layer so as to satisfy the relation d₁<

d₂ wherein d₁ is the well layer density on the first GaN-based compound semiconductor layer side in the active layer and d₂ is the well layer density on the second GaN-based compound semiconductor layer side.

21. The light illuminator according to claim 20, wherein light emitted from the GaN-based semiconductor light-emitting device is blue, and light emitted from the color conversion material is at least one type of light selected from the group consisting of yellow, green, and red.

22. The light illuminator according to claim 20, wherein the colors of light emitted from the GaN-based semiconductor light-emitting device and light emitted from the color conversion material are mixed to emit white light.

23. An image display device comprising a GaN-based semiconductor light-emitting device for displaying an image, the GaN-based semiconductor light-emitting device including:

(A) a first GaN-based compound semiconductor layer having n-type conductivity;

(B) an active layer having a multi-quantum well structure including well layers and barrier layers for separating between the well layers; and

(C) a second GaN-based compound semiconductor layer having p-type conductivity;

wherein the well layers are disposed in the active layer so as to satisfy the relation d₁<

d₂ wherein d₁ is the well layer density on the first GaN-based compound semiconductor layer side in the active layer and d₂ is the well layer density on the second GaN-based compound semiconductor layer side.

25. The image display device according to claim 23 or 24, further comprising a light valve.

26. The image display device according to claim 23 or 24, wherein the length of the short side or the short diameter of the active layer is 0.1 mm or less.

27. The image display device according to claim 23 or 24, wherein the length of the short side or the short diameter of the active layer is 0.03 mm or less.

24. An image display device comprising light-emitting device units for displaying a color image, which are arranged in a two-dimensional matrix and each of which includes a first light-emitting device emitting blue light, a second light-emitting device emitting green light, and a third light-emitting device emitting red light, a GaN-based semiconductor light emitting device constituting at least one of the first light-emitting device, the second light-emitting device, and the third light-emitting device including:

(A) a first GaN-based compound semiconductor layer having n-type conductivity;

(B) an active layer having a multi-quantum well structure including well layers and barrier layers for separating between the well layers; and

(C) a second GaN-based compound semiconductor layer having p-type conductivity;

wherein the well layers are disposed in the active layer so as to satisfy the relation d₁<

d₂ wherein d₁ is the well layer density on the first GaN-based compound semiconductor layer side in the active layer and d₂ is the well layer density on the second GaN-based compound semiconductor layer side.

28. A planar light source device for illuminating the back of a transmissive or transflective liquid crystal display device, the planar light source device comprising a GaN-based semiconductor light-emitting device provided as a light source, the GaN-based semiconductor light-emitting device including:

(A) a first GaN-based compound semiconductor layer having n-type conductivity;

(B) an active layer having a multi-quantum well structure including well layers and barrier layers for separating between the well layers; and

(C) a second GaN-based compound semiconductor layer having p-type conductivity;

wherein the well layers are disposed in the active layer so as to satisfy the relation d₁<

d₂ wherein d₁ is the well layer density on the first GaN-based compound semiconductor layer side in the active layer and d₂ is the well layer density on the second GaN-based compound semiconductor layer side.

29. A liquid crystal display assembly comprising a transmissive or transflective liquid crystal display device and a planar light source device for illuminating the back of the liquid crystal display device, a GaN-based semiconductor light-emitting device provided as a light source in the planar light source device including:

(A) a first GaN-based compound semiconductor layer having n-type conductivity;

(B) an active layer having a multi-quantum well structure including well layers and barrier layers for separating between the well layers; and

(C) a second GaN-based compound semiconductor layer having p-type conductivity;

wherein the well layers are disposed in the active layer so as to satisfy the relation d₁<

d₂ wherein d₁ is the well layer density on the first GaN-based compound semiconductor layer side in the active layer and d₂ is the well layer density on the second GaN-based compound semiconductor layer side.