  Point defects may introduce defect levels into the fundamental band gap of
the host semiconductors that alter the electrical properties of the material.
As a consequence, the in-gap defect levels and states automatically lower the
threshold energy of optical excitation associated with the optical gap of the
host semiconductor. It is, therefore, a common assumption that solid state
defect emitters in semiconductors ultimately alter the conductivity of the
host. Here we demonstrate on a particular defect in 4H silicon carbide that a
yet unrecognized class of point defects exists which are optically active but
electrically inactive in the ground state.
