Raman scattering on intrinsic surface electron accumulation of InN nanowires

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 $6.7×1016cm−3$⁠. The pronounced peak at $627.2cm−1$ is related to the interaction of phonons with surface electrons. The surface charge density, $Nsc$ is calculated to be $∼2.55×1013cm−2$ which provides surface accumulation field strength of 5.5 Mv/cm.