Conventionally, a semiconductor substrate made of SiC includes an epitaxial film which is arranged on the SiC substrate, and is made of SiC. The semiconductor substrate made of SiC is used for, for example, a PN diode and a bipolar transistor as a SiC semiconductor device.
The above semiconductor substrate is formed by growing the epitaxial film on a surface of the SiC substrate by a CVD (i.e., chemical vapor deposition) method with hydrogen as a carrier gas using the SiC substrate, which is prepared by crystal growth of a sublimation method under argon gas atmosphere.
In a case where the crustal growth of the SiC substrate is performed by the sublimation method, when the hydrogen gas is introduced into a growth chamber of the sublimation method so that the nitrogen is prevented from being absorbed into a growing crystal, it is possible to obtain the SiC single crystal with ultrahigh purity (see Patent Literature 1).