  The list of semiconductor materials with spectroscopically fingerprinted
self-interstitials is very short. The M-center in 4H-SiC, a bistable defect
responsible for a family of electron traps, has been deprived of a model which
could unveil its real importance for almost two decades. Using advanced
first-principles calculations and junction spectroscopy, we demonstrate that
the properties of M, including bistability, annealing, reconfiguration
kinetics, and electronic levels, match those of the carbon self-interstitial.
