  he correct estimation of thermal properties of ultra-scaled CMOS and
thermoelectric semiconductor devices demands for accurate phonon modeling in
such structures. This work provides a detailed description of the modified
valence force field (MVFF) method to obtain the phonon dispersion in
zinc-blende semiconductors. The model is extended from bulk to nanowires after
incorporating proper boundary conditions. The computational demands by the
phonon calculation increase rapidly as the wire cross-section size increases.
It is shown that the nanowire phonon spectrum differ considerably from the bulk
dispersions. This manifests itself in the form of different physical and
thermal properties in these wires. We believe that this model and approach will
prove beneficial in the understanding of the lattice dynamics in the next
generation ultra-scaled semiconductor devices.
