As-grown and pre-oxidized silicon carbide (SiC) samples of polytype 4H have been annealed at temperatures up to 1950 °C for 10 min duration using inductive heating, or at 2000 °C for 30 s using microwave heating. The samples consisted of a n-type high-purity epitaxial layer grown on 4° off-axis ⟨0001⟩ n+-substrate and the evolution of the carbon vacancy (VC) concentration in the epitaxial layer was monitored by deep level transient spectroscopy via the characteristic Z1/2 peak. Z1/2 appears at ∼0.7 eV below the conduction band edge and arises from the doubly negative charge state of VC. The concentration of VC increases strongly after treatment at temperatures ≥ 1600 °C and it reaches almost 1015 cm−3 after the inductive heating at 1950 °C. A formation enthalpy of ∼5.0 eV is deduced for VC, in close agreement with recent theoretical predictions in the literature, and the entropy factor is …