Nitride compound semiconductor light emitting device

• US 6,242,761 B1
• Filed: 02/20/1998
• Issued: 06/05/2001
• Est. Priority Date: 02/21/1997
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Rennie, John, Nunoue, Shinya, Yamamoto, Masahiro, Ishikawa, Masayuki, Fujimoto, Hidetoshi, Sugiura, Lisa
• Primary Examiner(s): WOJCIECHOWICZ, EDWARD JOSEPH
• Application Number:
  US09/026,941
• Time in Patent Office: 1,201 Days
• Field of Search: 257/94, 257/98, 257/102, 257/103, 257/618
• US Class Current: 257/94
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 5/2205 comprising special burying or current confinement layers
• CPC Class Codes: H01S 5/2206 based on III-V materials
• CPC Class Codes: H01S 5/2214 based on oxides or nitrides
• CPC Class Codes: H01S 5/2226 semiconductors with a specific doping
• CPC Class Codes: H01S 5/2231 with inner confining structure only between the active layer and the upper electrode
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

In order to remove the problems in conventional nitride compound semiconductor laser structures, namely, high operation voltage caused by a high resistance in a p-type layer and a high contact resistance of an electrode, damage to the crystal caused by dry etching, insufficient current injection, and the need for a high current density, a nitride compound semiconductor light emitting device has current blocking layers made of n-type B_{(1−x−y−z)}In_xAl_yGa_zN (0≦x≦1, 0≦y≦1, 0≦z≦1) single crystal containing an oxide of a predetermined metal, carbon and impurities exhibiting p-type and n-type conductivity, or i-type B_{(1−x−y−z)}In_xAl_yGa_zN (0≦x≦1, 0≦y≦1, 0≦z≦1) single crystal in which carriers are inactivated by hydrogen or oxygen to realize an internal current blocking structure without the need for dry etching. By applying a reverse bias voltage, the semiconductor can be activated only along a current path, and the remainder region is utilized as a current blocking layer. When the n-side electrode has a unique three-layered structure, a reduction in contact resistance and good wire bonding are promised.

Claims

1. A nitride compound semiconductor light emitting device including an active layer, a current blocking layer and a contact layer, wherein said current blocking layer has an opening so that a current can be selectively injected into said active layer, said current blocking layer is interposed between said active layer and said contact layer and said current blocking layer is made of an oxide of a metal selected from the group consisting of titanium (Ti), magnesium (Mg), nickel (Ni), chromium (Cr), scandium (Sc), zinc (Zn), indium (In), tin (Sn) and tungsten (W).

2. A nitride compound semitting device having an active layer and a current blocking layer, wherein said current blocking layer has an opening so that a current can be selectively injected into said active layer and said current blocking layer is made of i-type B₍₁₋

x−

y−

z)In_xAl_yGa_zN single-crystal (0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1) in which carriers are inactivated by hydrogen or oxygen.

3. A nitride compound semiconductor light emitting device having an active layer and a current blocking layer, wherein said current blocking layer has an opening so that a current can be selectively injected into said active layer and said current blocking layer is made of B₍₁₋

x−

y−

z)In_xAl_yGa_zN single-crystal (0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1) including magnesium and oxygen.

4. The nitride compound semiconductor light emitting device according to claim 3 wherein said current blocking layer is made of B₍₁₋

x−

y−

z)In_xAl_yGa_zN single-crystal (0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1).

5. A nitride compound semiconductor light emitting device having a current blocking layer, wherein said current blocking layer is made of an n-type B₍₁₋

x−

y−

z)In_xAl_yGa_zN single-crystal (0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1) containing both a p-type impurity and an n-type impurity.

6. The nitride compound semiconductor light emitting device according to claim 5 wherein said current blocking layer is made of n-type B₍₁₋

x−

y−

z)In_xAl_yGa_zN single-crystal (0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1).

7. A nitride compound semiconductor light emitting device comprising:

an electrically conductive nitride compound semiconductor layer;

a current blocking layer stacked on said nitride compound semiconductor layer and having an opening;

a buffer layer made of B<sub>(1−

x−

y−

z)</sub>In_xAl_yGa_zN (0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1) stacked to cover said current blocking layer and said nitride compound semiconductor layer at said opening; and

a layer made of B<sub>(1−

x2−

y2−

z2)</sub>In_x2Al_y2Ga_z2N (0≦

x2≦

1, 0≦

y2≦

1, 0≦

z2≦

1) stacked on said buffer layer.

8. The nitride compound semiconductor light emitting device according to claim 7 wherein said buffer layer has been initially stacked at a lower temperature then re-crystallized at a higher temperature.

9. The nitride compound semiconductor light emitting device according to claim 7 wherein said buffer layer has been initially stacked in an amorphous state then thereafter re-crystallized.

10. The nitride compound semiconductor light emitting device according to claim 7 wherein said buffer layer has been initially stacked in a polycrystalline state then thereafter re-crystallized.

11. The nitride compound semiconductor light emitting device according to claim 7 wherein said buffer layer is in a polycrystalline state.

12. The nitride compound semiconductor light emitting device according to claim 7 wherein said opening is stripe-shaped.

13. The nitride compound semiconductor light emitting device according to claim 7, further comprising a substrate and an active layer, and said current blocking layer being formed between said substrate and said active layer.

14. The nitride compound semiconductor light emitting device according to claim 7 wherein said current blocking layer is made of B₍₁₋

x−

y−

z)In_xAl_yGa_zN single-crystal (0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1) in which carriers are inactivated by hydrogen or oxygen.

15. The nitride compound semiconductor light emitting device according to claim 7 wherein said current blocking layer is B₍₁₋

x−

y−

z)In_xAl_yGa_zN (0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1) containing both a p-type impurity and an n-type impurity.

16. A nitride compound semiconductor light emitting device comprising:

a substrate;

a first buffer layer stacked on said substrate;

an electrically conductive layer stacked on said buffer layer and made of B<sub>(1−

x1−

y1−

z1)</sub>In_x1Al_y1Ga_z1N (0≦

x1≦

1, 0≦

y1≦

1, 0≦

z1≦

1);

a current blocking layer stacked on said electrically conductive layer and having an opening;

a second buffer layer stacked to cover said current blocking layer and said electrically conductive layer at said opening, said second buffer layer being made of a B<sub>(1−

x2−

y2−

z2)</sub>In_x2Al_y2Ga_z2N (0≦

z2≦

1, 0≦

y2≦

1, 0z2≦

1); and

an active layer stacked on said second buffer layer and made of B<sub>(1−

x3−

y3−

z3)</sub>In_x3Al_y3Ga_z3N (0≦

x3≦

1, 0≦

y3≦

1, 0≦

z3≦

1).

17. The nitride compound semiconductor light emitting device according to claim 16, wherein said current blocking layer is made of an oxide of a metal selected from the group consisting of titanium (Ti), magnesium (Mg), nickel (Ni), chromium (Cr), scandium (Sc), zinc (Zn), indium (In), tin (Sn) and tungsten (W).

18. The nitride compound semiconductor light emitting device according to claim 16, wherein said current blocking layer is made of i-type B₍₁₋

x−

y−

z)In_xAl_yGa_zN single-crystal layer (0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1) in which carriers are inactivated by hydrogen or oxygen.

19. The nitride compound semiconductor light emitting device according to claim 16, wherein said current blocking layer is made of i-type B₍₁₋

x−

y−

z)In_xAl_yGa_zN single-crystal layer (0≦

z≦

1, 0≦

y≦

1, 0≦

z≦

1) including a p-type impurity.