N-doped 6H–SiC wafers have been annealed in hot hydrogen for two doping levels, corresponding ton-(n∼1017 cm−3)andn+-type(n∼1019 cm−3)material. Electron spin resonance shows little passivation of N by hydrogen inn-type material, where secondary-ion-mass spectroscopy shows better penetration of deuterium. Both observations are accounted for in terms of Fermi-level control of the hydrogen charge state. ©1997 American Institute of Physics.