Epitaxial wafer for a semiconductor light emitting device, method for fabricating the same and semiconductor light emitting device

• US 7,622,745 B2
• Filed: 08/18/2006
• Issued: 11/24/2009
• Est. Priority Date: 08/30/2005
• Status: Expired due to Fees

• Current Assignee: Hitachi Cable Limited (Proterial Ltd.)
• Original Assignee: Hitachi Cable Limited (Proterial Ltd.)
• Inventors: Suzuki, Ryoji
• Primary Examiner(s): WILCZEWSKI, MARY A
• Application Number:
  US11/505,877
• Publication Number:
  US 20070045651A1
• Time in Patent Office: 1,194 Days
• Field of Search: 438/29, 438/46, 438/47, 438/761, 117/954, 257/94, 257/96, 257/97, 257/102, 257/103, 257/201, 257/615, 257/12, 257/13, 257/14, 257/E33.023, 257/E33.026, 257/E33.027, 257/E33.029, 257/E33.031, 257/E33.032, 257/E21.085
• US Class Current: 257/96
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 33/02 characterised by the semiconductor bodies
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/305 characterised by the doping materials
• CPC Class Codes: H01S 5/3054 p-doping
• CPC Class Codes: H01S 5/3072 Diffusion blocking layer, i.e. a special layer blocking diffusion of dopants
• CPC Class Codes: H01S 5/3211 characterised by special cladding layers, e.g. details on band-discontinuities
• CPC Class Codes: H01S 5/34313 with a well layer having only As as V-compound, e.g. AlGaAs, InGaAs
• CPC Class Codes: H01S 5/34326 with a well layer based on InGa(Al)P, e.g. red laser
• CPC Class Codes: H01S 5/34353 based on (AI)GaAs
• CPC Class Codes: H01S 5/3436 based on InGa(Al)P

Abstract

A n-type GaAs buffer layer 2, a n-type GaInP buffer layer 3, a n-type AlGaInP cladding layer 4, an undoped AlGaAs guide layer 5, an AlGaAs/GaAs multiquantum well (MQW) active layer 6, a first p-type AlGaInP cladding layer 7, a p-type GaInP etching stopper layer 8, a second p-type AlGaInP cladding layer 9, a C-doped AlGaAs layer (Zn-diffusion suppressing layer) 10, a p-type GaInP intermediate layer 11, and a p-type GaAs cap layer 12 are sequentially grown on a n-type GaAs substrate 1.

Claims

1. An epitaxial wafer for a semiconductor light emitting device, comprising:

an n-type cladding layer, an active layer, a p-type cladding layer, and a p-type cap layer sequentially grown on an n-type substrate,

wherein a p-type dopant of the p-type cap layer is Zn and a C-doped p-type AlGaAs layer is interposed between the p-type cladding layer and the p-type cap layer,

wherein the epitaxial wafer for the semiconductor light emitting device further comprises;

a p-type intermediate layer interposed between the C-doped p-type AlGaAs layer and the p-type cap layer;

a second p-type cladding layer; and

a p-type etching stopper layer interposed between the p-type cladding layer and the second p-type cladding layer, and

wherein the C-doped p-type AlGaAs layer is interposed between the second p-type cladding layer and the p-type intermediate layer.

2. The epitaxial wafer for a semiconductor light emitting device, according to claim 1, wherein:

the p-type intermediate layer comprises at least one layer comprised of GaInP or AlGaInP, and the bandgap wavelength of the C-doped p-type AlGaAs layer is longer than the bandgap wavelength of the p-type cladding layer and shorter than a bandgap wavelength of the p-type intermediate layer.

3. The epitaxial wafer for a semiconductor light emitting device, according to claim 1, wherein:

the second p-type cladding layer is comprised of AlGaInP.

4. The epitaxial wafer for a semiconductor light emitting device, according to claim 1, wherein:

the p-type etching stopper layer comprises at least one layer comprised of GaInP or AlGaInP.

5. The epitaxial wafer for a semiconductor light emitting device, according to claim 1, wherein:

a p-type dopant for the p-type cladding layer is Zn or Mg.

6. The epitaxial wafer for a semiconductor light emitting device, according to claim 1, wherein:

a p-type dopant for the second p-type cladding layer is Zn or Mg.

7. The epitaxial wafer for a semiconductor light emitting device, according to claim 1, wherein:

the p-type cap layer has a carrier concentration of 1×

10¹⁹/cm³ or more.

8. The epitaxial wafer for a semiconductor light emitting device, according to claim 1, wherein:

the C-doped p-type AlGaAs layer may have an Al composition ratio of 0.70 to 0.95.

9. An epitaxial wafer for a semiconductor light emitting device, comprising:

an n-type cladding layer, an active layer, a p-type cladding layer, and a p-type cap layer sequentially grown on an n-type substrate,

wherein a p-type dopant of the p-type cap layer is Zn and a C-doped p-type AlGaAs layer is interposed between the p-type cladding layer and the p-type cap layer,

wherein the n-type substrate is comprised of GaAs, the n-type cladding layer comprises at least one layer comprised of AlGaInP, the p-type cladding layer comprises at least one layer comprised of AlGaInP, the p-type cap layer is comprised of GaAs, and a bandgap wavelength of the C-doped p-type AlGaAs layer is longer than a bandgap wavelength of the p-type cladding layer,

wherein the epitaxial wafer for the semiconductor light emitting device further comprises;

a p-type intermediate layer interposed between the C-doped p-type AlGaAs layer and the p-type cap layer;

a second p-type cladding layer; and

a p-type etching stopper layer interposed between the p-type cladding layer and the second p-type cladding layer, and

wherein the C-doped p-type AlGaAs layer is interposed between the second p-type cladding layer and the p-type intermediate layer.

10. The epitaxial wafer for a semiconductor light emitting device, according to claim 9, wherein:

the p-type intermediate layer comprises at least one layer comprised of GaInP or AlGaInP, and the bandgap wavelength of the C-doped p-type AlGaAs layer is longer than the bandgap wavelength of the p-type cladding layer and shorter than a bandgap wavelength of the p-type intermediate layer.

11. The epitaxial wafer for a semiconductor light emitting device, according to claim 9, wherein:

the second p-type cladding layer is comprised of AlGaInP.

12. The epitaxial wafer for a semiconductor light emitting device, according to claim 9, wherein:

the p-type etching stopper layer comprises at least one layer comprised of GaInP or AlGaInP.

13. The epitaxial wafer for a semiconductor light emitting device, according to claim 9, wherein:

a p-type dopant for the p-type cladding layer is Zn or Mg.

14. The epitaxial wafer for a semiconductor light emitting device, according to claim 9, wherein:

a p-type dopant for the second p-type cladding layer is Zn or Mg.

15. The epitaxial wafer for a semiconductor light emitting device, according to claim 9, wherein:

the p-type cap layer has a carrier concentration of 1×

10¹⁹/cm³ or more.

16. The epitaxial wafer for a semiconductor light emitting device, according to claim 9, wherein:

the C-doped p-type AlGaAs layer may have an Al composition ratio of 0.70 to 0.95.

17. A semiconductor light emitting device, fabricated by using an epitaxial wafer for a semiconductor light emitting device comprising a n-type cladding layer, an active layer, a p-type cladding layer, and a p-type cap layer sequentially grown on an n-type substrate, wherein:

a p-type dopant of the p-type cap layer is Zn and a C-doped p-type AlGaAs layer is interposed between the p-type cladding layer and the p-type cap layer;

the n-type substrate is comprised of GaAs, the n-type cladding layer comprises at least one layer comprised of AlGaInP, the p-type cladding layer comprises at least one layer comprised of AlGaInP, the p-type cap layer is comprised of GaAs, and a bandgap wavelength of the C-doped p-type AlGaAs layer is longer than a bandgap wavelength of the p-type cladding layer,

the epitaxial wafer for the semiconductor light emitting device further comprises;

a p-type intermediate layer interposed between the C-doped p-type AlGaAs layer and the p-type cap layer;

a second p-type cladding layer; and

a p-type etching stopper layer interposed between the p-type cladding layer and the second p-type cladding layer, and

the C-doped p-type AlGaAs layer is interposed between the second p-type cladding layer and the p-type intermediate layer.

18. A method for fabricating an epitaxial wafer for a semiconductor light emitting device, comprising the step of:

epitaxially growing an n-type cladding layer, an active layer, a p-type cladding layer, a C-doped p-type AlGaAs layer, and a p-type cap layer sequentially on a n-type substrate,

wherein;

a p-type dopant of the p-type cap layer is Zn and a C-doped p-type AlGaAs layer is, as a result of the method, interposed between the p-type cladding layer and the p-type cap layer,

wherein the n-type substrate is comprised of GaAs, the n-type cladding layer comprises at least one layer comprised of AlGaInP, the p-type cladding layer comprises at least one layer comprised of AlGaInP, the p-type cap layer is comprised of GaAs, and a bandgap wavelength of the C-doped p-type AlGaAs layer is longer than a bandgap wavelength of the p-type cladding layer,

wherein, as a result of the method, the epitaxial wafer for the semiconductor light emitting device further comprises;

a p-type intermediate layer interposed between the C-doped p-type AlGaAs layer and the p-type cap layer;

a second p-type cladding layer; and

a p-type etching stopper layer interposed between the p-type cladding layer and the second p-type cladding layer, and

wherein, as a result of the method, the C-doped p-type AlGaAs layer is interposed between the second p-type cladding layer and the p-type intermediate layer.

19. The method for fabricating an epitaxial wafer for a semiconductor light emitting device, according to claim 18, wherein:

the C-doped p-type AlGaAs layer is doped by conducting auto-doping of a metalorganic source by adjusting a V/III ratio between a III group source and a V group source.

20. The method for fabricating an epitaxial wafer for a semiconductor light emitting device, according to claim 18, wherein:

the C-doped p-type AlGaAs layer is doped by conducting auto-doping of a metalorganic source by adjusting a growth temperature.