Abstract: Embodiments related to a method of forming semi-insulating silicon carbide (SiC) single crystal are disclosed in which shallow donor levels originating, at least in part, from residual nitrogen impurities are compensated by the addition of one or more trivalent element(s) introduced by doping the SiC in a concentration that changes the SiC conductivity from n-type to semi-insulating. Related embodiments provide for the additional doping of the SiC single crystal with one or more deep level dopants. However, the resulting concentration of deep level dopants, as well as shallow donor or acceptor dopants, is not limited to concentrations below the detection limits of secondary ion mass spectrometry (SIMS) analysis.