The hydrogen depth distribution in 4H-SiC after epitaxial growth at 1600 degreesC has been studied in detail with secondary ion mass spectrometry. Both H-1 and H-2 have been employed as carrier gas to trace the origin of the incorporated hydrogen. In particular the substrate as a prospective hydrogen source has been considered. After growth H-2 is detected throughout the whole substrate (similar to400 mum) and a considerable quantity remains after annealing at 1500 degreesC for 15 minutes.