Before revision: They are "deep" in the sense that the energy required to remove an electron or hole from the trap to the valence or conduction band is much larger than the characteristic thermal energy kT, where k is the Boltzmann constant and T is temperature.
After revision: They are "deep" in the sense that the energy required to remove an electron or hole from the trap to the valence or conduction band is much larsadasdaddadasdger than the characteristic thermal energy kT, where k is the Boltzmann constant and T is temperature.