The understanding of the structure and associated defect level of a point defect in SiC is important because the material is to be used both as a semiconductor and semi-insulator. Production of the latter is achieved by compensation of unavoidable impurities using defects that require more energy for ionization than the unintentional donors or acceptors. The purpose of the present work is to measure the defect energy level of one center in high resistivity 4H SiC using photo-induced electron paramagnetic resonance (photo-EPR). The center is identified as SI-5, an EPR signal that others have attributed to the negative charge state of the carbon vacancy carbon antisite pair, V CC Si- The photo-threshold for detection of the signal is 0.75 eV in samples with resistivity activation energy, E a, of 0.5 eV or smaller. For samples with larger E a, SI-5 is detected only after irradiation with photon energy greater than 2.5 eV. The results suggest that V C C Si-/- is 0.75 eV below the conduction band edge and that the negative to neutral level is within 0.1 eV of V CC Si-/-. © Springer Science+Business Media, LLC 2007.