Epitaxial silicon carbide single crystal wafer and process for producing the same

An epitaxial silicon carbide single crystal wafer comprising:

• a silicon carbide single crystal substrate having an off angle of 4° or less, which is an angle tilted in the <11-20> direction with respect to the (0001) plane;
• a buffer layer, formed on the silicon carbide single crystal substrate, having a doping density of 1×1018 atms/cm3 or more and 1×1019 atms/cm3 or less and consisting of a silicon carbide epitaxial film having a thickness of 1 μm or more and 10 μm or less;
• and
• a drift layer, formed on the buffer layer, having a doping density of 1×1015 atms/cm3 or more and 1×1017 atms/cm3 or less and consisting of a silicon carbide epitaxial film having a thickness of 10 μm or more and 30 μm or less,
• wherein
• the depth of the shallow pits on the surface of the drift layer is 30 nm or less, and
• when a Schottky barrier diode is formed by providing a Ni-based ohmic electrode on the side of the silicon carbide single crystal substrate and a Ni-based Schottky electrode on the side of the drift layer, the leakage current at a reverse applied voltage of 400 V becomes 1×10−11 A/cm2 or more and 1×10−8 A/cm2 or less.