a A bright state of a color center under optical excitation. b These incident photons may ionize the defect and turn it into a dark state while also, c, does not have sufficient energy to repopulate the bright state. d In a quantum well, however, the excitation laser can successfully re-pump the bright state. e Band structure of a defective 4H-SiC including a stacking fault. Red curves depict bulk-like conduction and valence band states in the basal plane of the hexagonal Brillouin zone. Purple curves show the stacking fault states that localized in c direction and dispersive in the basal plane.