Structural properties and Raman modes of zinc blende InN epitaxial layers

We report on x-ray diffraction and micro-Raman scattering studies on zinc b lende InN epitaxial films. The samples were grown by molecular beam epitaxy on GaAs(001) substrates using a InAs layer as a buffer. The transverse-opt ical (TO) and longitudinal-optical phonon frequencies at Gamma of c-InN are determined and compared to the corresponding values for c-GaN. Ab initio s elf-consistent calculations are carried out for the c-InN c-GaN lattice par ameters and TO phonon frequencies. A good agreement between theory and expe riment is found. (C) 1999 American Institute of Physics. [S0005-6951(99)005 03-3].