GaN-based semiconductor light-emitting device, light illuminator, image display planar light source device, and liquid crystal display assembly

• US 8,168,966 B2
• Filed: 09/08/2006
• Issued: 05/01/2012
• 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: Biwa, Goshi, Okuyama, Hiroyuki
• Primary Examiner(s): Nguyen, Cuong Q
• Assistant Examiner(s): Gebreyesus, Yosef
• Application Number:
  US11/718,862
• Publication Number:
  US 20070284564A1
• Time in Patent Office: 2,062 Days
• Field of Search: 257/9, 257/13, 257/14, 257/15, 257/96, 257/97, 257/E33.008, 257/E33.009, 257/E33.01, 257/E31.033, 257/E31.035, 257/E31.036, 257/E29.072, 257/E29.074, 257/E29.298, 257/22, 257/103, 257/E33.034, 257/79, 257/94, 257/615, 257/E33.108, 438/22, 438/46, 438/47
• 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;

a thickness of t₀; and

a first region extending from the first GaN-based compound layer to a thickness of approximately (2t₀/3) in the active layer, the first region having a well layer density of d₁; and

a second region that is separate from the first region and having a well layer density of d₂; and

(C) a second GaN-based compound semiconductor layer having p-type conductivity, the second region of the active layer extending from the second GaN-based compound layer to a thickness of approximately (t₀/3) in the active layer;

wherein the first GaN-based compound layer is located closer to a substrate than the second GaN-based compound layer,

wherein the well layers are disposed in the first and second regions of the active layer

and the thicknesses of successive barrier layers decrease or remain the same from the first GaN-based compound semiconductor layer side to the second GaN-based compound semiconductor layer side so as to satisfy the relation d₁<

d₂, and and

wherein the thicknesses of the barrier layers decrease at least twice from the first GaN-based compound semiconductor layer side to 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 (t₀/2) 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.

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 (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.

8. 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.

9. 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.

10. The GaN-based semiconductor light-emitting device according to claim 1, wherein the at least one well layer and the other well layers include an approximate 0.23 to 0.77 ratio of indium atoms to gallium atoms.

11. 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.

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

(D) an underlying layer containing indium 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.

13. 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.

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

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

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

adjust a peak current to control a quantity of light emitted from the GaN-based semiconductor light-emitting device;

adjust a pulse width to control the quantity of light emitted from the GaN-based semiconductor light-emitting device; and

adjust a number of pulses in an operational period to control the quantity of light emitted from the GaN-based semiconductor light-emitting device.

17. The GaN-based semiconductor light-emitting device according to claim 1, wherein at least one of the well layers having a different ratio of indium atoms to gallium atoms from the other well layers and the thickness of a first barrier layer nearest the second GaN-based compound semiconductor layer is twice or more the thickness of a second barrier layer nearest the first GaN-based compound semiconductor layer.