Group III nitride semiconductor light emitting device

• US 7,456,445 B2
• Filed: 05/20/2005
• Issued: 11/25/2008
• Est. Priority Date: 05/24/2004
• Status: Expired due to Fees

• Current Assignee: Showa Denko KK
• Original Assignee: Showa Denko KK
• Inventors: Takeda, Hitoshi, Horikawa, Syunji
• Primary Examiner(s): Pert; Evan
• Assistant Examiner(s): Wilson; Scott R
• Application Number:
  US11/597,384
• Publication Number:
  US 20070228407A1
• Time in Patent Office: 1,285 Days
• Field of Search: None
• US Class Current: 257/200
• CPC Class Codes: H01L 33/305 characterised by the doping materials
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/325 characterised by the doping materials

Abstract

A Group III nitride semiconductor light emitting device having a light emitting layer (6) bonded to a crystal layer composed of an n-type or p-type Group III nitride semiconductor, the Group III nitride semiconductor light emitting device being characterized by comprising an n-type Group III nitride semiconductor layer (4) having germanium (Ge) added thereto and having a resistivity of 1×10⁻¹ to 1×10⁻³ Ωcm. The invention provides a Ge-doped n-type Group III nitride semiconductor layer with low resistance and excellent flatness, in order to obtain a Group III nitride semiconductor light emitting device exhibiting low forward voltage and excellent light emitting efficiency.

Claims

1. A Group III nitride semiconductor light emitting device having an n-type contact layer, a light emitting layer, and a p-type layer, composed of a Group III nitride semiconductor,

wherein the n-type contact layer has a structure with periodic alternating lamination of a germanium (Ge)-added Group III nitride semiconductor layer and an undoped Group III nitride semiconductor layer,

wherein the layer thickness of the Ge-added Group III nitride semiconductor layer is equal to or less than the layer thickness of the undoped Group III nitride semiconductor layer, and

wherein the n-type contact layer has a resistivity of 1×

10<sup>−

2</sup> to 3 ×

10<sup>−

3</sup> Ω

cm.

2. A Group III nitride semiconductor light emitting device according to claim 1, wherein the n-type contact layer has the compositional formula Al_xGa_yIn_zN_l−

aM _a (wherein 0≦

×

≦

1, 0≦

y≦

1,0≦

z≦

1,x+y+z=1,M represents a Group V element other than nitrogen (N) and 0≦

a<

1).

3. A Group III nitride semiconductor light emitting device according to claim 1, wherein the Ge atom concentration in the Ge-added Group III nitride semiconductor layer is at least 1×

10¹⁷ cm<sup>−

3</sup> and no greater than 1×

10²⁰ cm<sup>−

3</sup> .

4. A Group III nitride semiconductor light emitting device according to claim 1, wherein the n-type Group III nitride semiconductor layer is situated between a substrate and the light emitting layer.

5. A Group III nitride semiconductor light emitting device according to claim 1, wherein the total layer thickness in the region in which the Ge atom concentration varies in a periodic manner is at least 0.1 μ

m and no greater than 10 μ

m.

6. A Group III nitride semiconductor light emitting device according to claim 1, wherein the layer thickness of one period in the region in which the Ge atom concentration varies in a periodic manner is at least 1 nm and no greater than 1000 nm.

7. An LED employing a Group III nitride semiconductor light emitting device according to claim 1.

8. A lamp employing a light emitting device according to claim 7.

9. A process for fabrication of a Group III nitride semiconductor light emitting device having a light emitting layer bonded to a crystal layer composed of an n-type or p-type Group III nitride semiconductor, the process being characterized in that during growth of the Ge-added n-type Group III nitride semiconductor layer, Ge atom is supplied to the reaction system in a periodically varying manner.