Raman scattering characterization of annealed GaNxAs1-x layers

Raman scattering from the GaNxAs1-x layers grown on the (001) GaAs substrates has been investigated to characterize the locally ordered structures in the grown layers. New optical phonon modes from the confined GaAs and GaN structures and the disorder activated modes were observed. These new modes strongly suggest the presence of the trigonal {111}-(GaN)(1)(GaAs)(1) natural superlattice cluster in the GaNxAs1-x layers. A thermal annealing effect has been also investigated through the variation of the confined GaAs- and the GaN-like modes and we have confirmed that the hydrogen (H) atoms included in the as-grown GaNxAs1-x layers desorb from the layers by the annealing. The results strongly indicate that the H-induced degradation in the natural superlattice cluster are recovered through breaking of the N-H bonds by the annealing.