We investigated the thermoelectric properties of 4H-SiC substrates and dense sintered SiC, which are expected to be candidate materials for use in self-cooling devices because of their high Seebeck coefficient, low electrical resistivity, and high thermal conductivity. The carrier concentration of 4H-SiC samples doped with nitrogen is in the range of 1016 to 1019 cm-3. The sintered SiC samples of the α-type and β-type contain less than 1000 ppm of cation impurities and have a relative density higher than 98% with respect to single-crystalline SiC. 4H-SiC with a carrier concentration of 1019 cm-3 has the highest power factor of 2.7 ×10-3 WcenterdotK-2centerdotm-1 and a high thermal conductivity of 260 WcenterdotK-1centerdotm-1 at room temperature. One-dimensional calculations for heat distribution indicate that a Si chip in a self-cooling device, which consists of 4H-SiC with a carrier concentration of 1019 cm-3, could be refrigerated more strongly than one on a copper plate under specific operating conditions.