Structural and vibrational properties of dilute GaNxAs1−x(P1−x)

We report a comprehensive analyzes of the Fourier transform infrared (FTIR) absorption and Raman scattering data on the structural and vibrational properties of dilute ternary GaAs_1−xN_x,GaP_1−xN_x] (x<0.03) alloys grown on GaAs GaP] by metal organic chemical vapor deposition (MOCVD) and solid source molecular beam epitaxy (MBE). By using realistic total energy and lattice dynamical calculations, the origin of experimentally observed N-induced vibrational features are characterized. Useful information is obtained about the structural stability, vibrational frequencies, lattice relaxations and compositional disorder in GaNAs (GaNP) alloys. At lower composition (x<0.015) most of the N atoms occupy the As P] sublattice {N_AsN_P]}—they prefer moving out of their substitutional sites to more energetically favorable locations at higher x. Our results for the N-isotopic shifts of local mode frequencies compare favorably well with the existing FTIR data.