An intrinsic property of vertically aligned InN nanowire (NW) ensembles have been investigated by analysis of coupled longitudinal optical (LO) phonon mode using μ-Raman scattering. Spectra were recorded in backscattering geometries in parallel and perpendicular to the axis of the NWs. The width of surface accumulation layer is estimated from the LO phonon peak intensity ratios. The carrier concentration is extracted to be 6.7×1016 cm−3. The pronounced peak at 627.2 cm−1 is related to the interaction of phonons with surface electrons. The surface charge density, Nsc is calculated to be ∼2.55×1013 cm−2 which provides surface accumulation field strength of 5.5 Mv/cm.