Nitride compound semiconductor element

• US 7,176,479 B2
• Filed: 02/09/2004
• Issued: 02/13/2007
• Est. Priority Date: 07/06/2001
• Status: Expired due to Term

• Current Assignee: Seoul Semiconductor Co., Ltd.
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ohba, Yasuo
• Primary Examiner(s): Soward; Ida M.
• Application Number:
  US10/773,297
• Publication Number:
  US 20040155250A1
• Time in Patent Office: 1,100 Days
• Field of Search: 257 11- 12, 257 14- 15, 257/20, 257/24, 257/51, 257 66- 67, 257/69, 257/70, 257/75, 257 96- 97, 257101-103, 257/94, 257/184, 257/189, 257/615
• US Class Current: 257/12
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02502 consisting of two layers
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/66924 with an active layer made of a group 13/15 material H01L29/66446 takes precedence
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A nitride compound semiconductor element having improved characteristics, productivity and yield. A nitride compound semiconductor element includes: a sapphire substrate; a first single crystalline layer of AlN formed on said sapphire substrate; a second single crystalline layer formed on said first single crystalline layer, said second single crystalline layer being made of Al_xGa_1-xN (0.8≦x≦0.97) and having a thickness of equal to or more than 0.3 μm and equal to or less than 6 μm; and a device structure section of a nitride semiconductor formed on said second single crystalline layer.

Claims

1. A nitride compound semiconductor element comprising:

a sapphire substrate;

a first single crystalline layer of AlN formed on said sapphire substrate;

a second single crystalline layer formed on said first single crystalline layer, said second single crystalline layer being made of Al_xGa_1-xN (0.85≦

x≦

0.95) and having a thickness of equal to or more than 0.7 μ

m and equal to or less than 3 μ

m; and

a device structure section of a nitride compound semiconductor formed on said second single crystalline layer,

wherein said first single crystalline layer is doped with carbon having a concentration of equal to or more than 3×

10¹⁸ cm<sup>−

3</sup> and equal to or less than 1×

10²⁰ cm<sup>−

3</sup>.

2. The nitride compound semiconductor element according to claim 1, wherein said sapphire substrate either has no warp or is warped concavely toward said device structure section.

3. The nitride compound semiconductor element according to claim 1, further comprising:

a single crystalline AlN protective layer formed directly on said second single crystalline layer for preventing Ga atoms from evaporating from said second single crystalline layer to thereby protect said second single crystalline layer, said AlN protective layer having a thickness of equal to or more than 1 nm and equal to or less than 10 nm.

4. The nitride compound semiconductor element according to claim 1, further comprising:

an AlN layer formed between said first single crystalline layer and said second single crystalline layer, said AlN layer containing no impurity or containing impurity having a concentration of less than 3×

10¹⁸ cm<sup>−

3</sup>.

5. A method of making a nitride compound semiconductor element, the method comprising

providing a sapphire substrate;

depositing on the sapphire substrate a first single crystalline layer of AlN;

depositing on the first single crystalline layer a second single crystalline layer of Al_xGa_1-xN (0.85≦

x≦

0.95) having a thickness of equal to or more than 0.7 μ

m and equal to or less than 3 μ

m;

depositing on the second single crystalline layer a device structure section of a nitride compound semiconductor; and

producing the semiconductor element of claim 1.

6. The nitride compound semiconductor element according to claim 1, wherein said nitride compound semiconductor element comprises a semiconductor laser.

7. The nitride compound semiconductor element according to claim 1, wherein said first single crystalline layer of AlN has a thickness of equal to or more than 10 nm and equal to or less than 50 nm.

8. The nitride compound semiconductor element according to claim 1, wherein said nitride compound semiconductor element comprises a semiconductor laser and wherein said device structure section comprises:

a first conductive-type semiconductor layer;

an active layer formed on said first conductive-type semiconductor layer for emitting light by current injection; and

a second conductive-type semiconductor layer formed on said active layer.

9. The nitride compound semiconductor element according to claim 8, wherein said active layer contains a well layer made of Ga_1-zIn_zN (0.15≦

z 0.3).

10. The nitride compound semiconductor element according to claim 1, further comprising:

a lattice modification layer formed between said second single crystalline layer and said device structure section, said lattice modification layer being made of Al_yGa_1-yN (0.25≦

y≦

0.75) and having a thickness of equal to or more than 0.3 μ

m and equal to or less than 3 μ

m.

11. The nitride compound semiconductor element according to claim 10, wherein said nitride compound semiconductor element comprises an optical switch or a field effect transistor.

12. The nitride compound semiconductor element according to claim 10, wherein said device structure section has a heterojunction of an AlN layer and a GaN layer.

13. The nitride compound semiconductor element according to claim 12, wherein said nitride compound semiconductor element comprises an optical switch.