  We explored the surface enhanced Raman scattering (SERS) activity of the InN
nanostructures, possessing surface electron accumulation (SEA), using the
Rhodamine 6G (R6G) molecules. SERS enhancement is observed for the InN
nanostructures which possess surface electron accumulation (SEA). In case of
high temperature grown InN samples, a peak is observed in the low wave number
(THz region) of Raman spectra of InN nanostructures originating from excitation
of the two dimensional (2D) plasmons of the SEA. The enhancement factor of four
orders was calculated with the assumption of monolayer coverage of analyte
molecule. SERS enhancement of InN nanostructures is attributed to the 2D
plasmonic nature of InN nanostructures invoking SEA, rather than the
contributions from 3D surface plasmon resonance (SPR) and chemical interaction.
The role of 2D plasmon excitation in SERS enhancement is corroborated by the
near-field light-matter interaction studies using near-field scanning optical
microscopy.
