N-type SiC single crystal and method for its production

Patent metadata

Field	Value
Publication number	US-10167570-B2
Application number	US-201414914823-A
Country	US
Kind code	B2
Filing date	Jul 23, 2014
Priority date	Aug 30, 2013
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

A n-type SiC single crystal with low resistivity and low threading dislocation density is provided, which is achieved by a n-type SiC single crystal containing germanium and nitrogen, wherein the density ratio of the germanium and the nitrogen [Ge/N] satisfies the relationship 0.17<[Ge/N]<1.60.

First claim

What is claimed is:

1. A n-type SiC single crystal, which is grown on a SiC seed crystal substrate, the n-type SiC single crystal comprising germanium and nitrogen, wherein the density ratio of the germanium and the nitrogen [Ge/N] satisfies the relationship 0.24≤[Ge/N]≤0.83,
the nitrogen density [N] satisfies the relationship 1.00×10 19 /cm 3 ≤[N]≤1.00×10 20 /cm 3 ,
the germanium density [Ge] satisfies the relationship 1.70×10 18 /cm 3 <[Ge]<1.60×10 20 /cm 3 , and the n-type SiC single crystal has a resistivity of 10 mΩ·cm or lower, and the same threading dislocation density level as the seed crystal substrate.

2. A method for producing the n-type SiC single crystal of claim 1 , the method comprising:
contacting the SiC seed crystal substrate with a Si—C solution having a temperature gradient such that the temperature decreases from the interior of the solution toward the surface of the solution, to cause crystal growth of the n-type SiC single crystal,
adding a nitride and germanium metal to the Si—C solution, and
growing the n-type SiC single crystal containing germanium and nitrogen, and
wherein the density ratio of the germanium and the nitrogen [Ge/N] satisfies the relationship 0.24≤[Ge/N]≤0.83,
the nitrogen density [N] satisfies the relationship 1.00×10 19 /cm 3 ≤[N]≤1.00×10 20 /cm 3 , and
the germanium density [Ge] satisfies the relationship 1.70×10 18 /cm 3 <[Ge]<1.60×10 20 /cm 3 .

3. The method according to claim 2 , wherein the nitride is at least one selected from the group consisting of chromium nitride, silicon nitride, germanium nitride, titanium nitride and nickel nitride.

4. The method according to claim 2 , wherein the amount of the nitride added is 0.12 at % or greater in terms of nitrogen atoms, based on the total amount of the Si—C solution containing nitrogen and germanium.

5. The method according to claim 2 , wherein the surface temperature of the Si—C solution is 1800 to 2200° C.

6. The method according to claim 3 , wherein the amount of the nitride added is 0.12 at % or greater in terms of nitrogen atoms, based on the total amount of the Si—C solution containing nitrogen and germanium.

7. The method according to claim 3 , wherein the surface temperature of the Si—C solution is 1800 to 2200° C.

8. The method according to claim 4 , wherein the surface temperature of the Si—C solution is 1800 to 2200° C.

Assignees

• Toyota Motor Co Ltd

Inventors

• Shirai Takayuki

Classifications

• C30B23/00

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• C30B19/04 Primary

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• C30B19/067

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• C30B19/062

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• C30B29/66

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