Group-III nitride semiconductor freestanding substrate and manufacturing method of the same

• US 8,102,026 B2
• Filed: 09/10/2009
• Issued: 01/24/2012
• Est. Priority Date: 04/13/2009
• Status: Active Grant

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Hitachi Cable Limited (Proterial Ltd.)
• Inventors: Eri, Takeshi, Meguro, Takeshi
• Primary Examiner(s): Wilson, Allan R
• Application Number:
  US12/556,635
• Publication Number:
  US 20100258812A1
• Time in Patent Office: 866 Days
• Field of Search: 257/615, 257/E29.089, 257/E29.093, 257/E21.135, 438/478, 438/495, 438/499, 438/501, 438/505, 438/508
• US Class Current: 257/615
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD

Abstract

To provide a group-III nitride semiconductor freestanding substrate, with carrier concentration of a peripheral part of a n-type group-III nitride semiconductor freestanding substrate set to be lower than the carrier concentration inside of the peripheral part. In this freestanding substrate, preferably value Δσ obtained by dividing a difference between a maximum value of the carrier concentration and a minimum value of the carrier concentration in a surface of the freestanding substrate by the maximum value of the carrier concentration is greater than 0.05, and the carrier concentration in any place in the surface of the freestanding substrate exceeds 5.0×10¹⁷ cm⁻³.

Claims

1. A group-III nitride semiconductor freestanding substrate, with carrier concentration of a peripheral part of a n-type group-III nitride semiconductor freestanding substrate set to be lower than the carrier concentration inside of the peripheral part.

2. The group-III nitride semiconductor freestanding substrate according to claim 1, wherein value Δ

σ

obtained by dividing a difference between a maximum value of the carrier concentration and a minimum value of the carrier concentration in a surface of the freestanding substrate by the maximum value of the carrier concentration is greater than 0.05, and the carrier concentration in any place in the surface of the freestanding substrate exceeds 5.0×

10¹⁷ cm<sup>−

3</sup>.

3. The group-III nitride semiconductor freestanding substrate according to claim 2, wherein the value Δ

σ

is 0.18 or less.

4. The group-III nitride semiconductor freestanding substrate according to claim 2, wherein the value Δ

σ

is 0.13 or more and 0.18 or less.

5. The group-III nitride semiconductor freestanding substrate according to claim 1, wherein a main surface of the group-III nitride semiconductor freestanding substrate is any one of C-face, M-face, or A-face.

6. The group-III nitride semiconductor freestanding substrate according to claim 1, wherein the carrier concentration is decreased gradually toward the peripheral part from a center part of the group-III nitride semiconductor substrate.

7. The group-III nitride semiconductor freestanding substrate according to claim 1, wherein the carrier concentration is highest in an intermediate part between a center part and the peripheral part of the group-III nitride semiconductor freestanding substrate, and the carrier concentration is decreased from the intermediate part to the peripheral part.

8. The group-III nitride semiconductor freestanding substrate according to claim 1, wherein the group-III nitride semiconductor freestanding substrate is a GaN substrate.

9. The group-III nitride semiconductor freestanding substrate according to claim 1, wherein n-type dopant of the group-III nitride semiconductor freestanding substrate is Si.

10. The group-III nitride semiconductor freestanding substrate according to claim 1, wherein the group-III nitride semiconductor freestanding substrate has a thickness of 200 μ

m or more, and a diameter of 2 inch or more.