Resonant Raman scattering studies of localized impurity states in semiconductors

We review resonant Raman scattering studies of GaAs_1-xN _x, where nitrogen impurities are spatially localized in the host GaAs. The conventional intensity resonance could provide symmetry information regarding nitrogen-induced states, such as E₊, which turned out to have significant components of an L and an X character, in addition to a Y character. We also observed the rather unusual and distinctive phonon linewidth resonance due to spatially locaUzed intermediate states that originated from a splitting of the L-point conduction band. We show that the resonant Raman scattering response, including asymmetric linewidth broadening resonances, can provide a powerful means to study semiconductor systems with strongly localized impurity states.