The evolution of deep levels that depend upon annealing temperature is investigated for n-type 4H SiC-Ni Schottky barriers. Several samples, cut from the same wafer, have been left unheated or annealed at 400°C, 700°C and 900°C, in air. Deep level transient spectroscopy (DLTS) has been used to investigate deep levels in all four sets of samples. Electron traps with activation energies EC-ET = 0.19 to 0.5 eV are observed, as well as a hole trap in the sample annealed at 900°C at energy ET-EV = 0.14 eV.