n-Type 4H—SiC single crystal substrate and method of producing n-type 4H—SiC single crystal substrate
In an n-type 4H-SiC single crystal substrate of the present disclosure, the concentration of the element N as a donor and the concentration of the element B as an acceptor are both 3×10 18 /cm 3 or more, and a threading dislocation density is less than 4,000/cm 2 .
1. An n-type 4H-SiC single crystal substrate in which a concentration of a donor element and a concentration of an acceptor element are both 3.0×10 18 /cm 3 or more, and a threading dislocation density is less than 4,000/cm 2 ,
wherein the threading dislocation includes threading screw dislocation, threading edge dislocation, and threading mixed dislocation.
2. The n-type 4H-SiC single crystal substrate according to claim 1 , wherein the concentration of the acceptor element is 3.0×10 18 /cm 3 or more and less than 2.0×10 19 /cm 3 .
3. The n-type 4H-SiC single crystal substrate according to claim 1 ,
wherein the acceptor element is boron (B).
4. The n-type 4H-SiC single crystal substrate according to claim 2 ,
wherein the acceptor element is boron (B).
5. The n-type 4H-SiC single crystal substrate according to claim 1 ,
wherein the donor element is nitrogen (N).
6. A method of producing an n-type 4H-SiC single crystal substrate according to claim 1 , comprising:
a process of filling a crucible with a raw material containing a silicon source (Si), a carbon source(C), and an element as an acceptor;
a process of pre-sublimating 0.1 mass% or more of the raw material in the crucible;
a process of disposing a seed crystal to face the raw material; and
a process of supplying a gas containing an element as a donor into the crucible, sublimating the pre-sublimated raw material in the crucible, and allowing a single crystal layer to grow on a surface of the seed crystal.
7. The method of producing an n-type 4H-SiC single crystal substrate according to claim 6 , wherein the acceptor is boron (B).
8. The method of producing an n-type 4H-SiC single crystal substrate according to claim 6 ,
wherein the donor is nitrogen (N).