  UV Raman scattering studies show longitudinal optical (LO) mode up to 4th
order in wurtzite GaN nanowire system. Frohlich interaction of electron with
the long range electrostatic field of ionic bonded GaN gives rise to
enhancement in LO phonon modes. Good crystalline quality, as indicated by the
crystallographic as well as luminescence studies, is thought to be responsible
for this significant observation. Calculated size dependence, incorporating
size corrected dielectric constants, of electron-phonon interaction energy
agrees well with measured values and also predict stronger interaction energy
than that of the bulk for diameter below ~3 nm.
