Carrier concentrations in GaN nanowire clusters grown by plasma-assisted MBE on Si(111) wafers were measured by Stokes Raman spectroscopy with 1.96 eV (633 nm) excitation. A simple model of longitudinal optical (LO) phonon - plasmon coupling was used to estimate the carrier concentration from the blue shift of the LO phonon peak in doped relative to undoped samples. The LO phonon peak occurred at 739.5 cm<SUP>−1</SUP> in a nominally undoped sample. Carrier concentrations of the doped samples, as determined by the peak shift method, varied from 1×10<SUP>17</SUP> cm<SUP>−3</SUP> to 8×10<SUP>17</SUP> cm<SUP>−3</SUP>. In addition, carrier concentrations and mobilities of single-nanowire electrical devices, fabricated from the as-grown samples examined by Raman spectroscopy, were estimated from UV-excited photocurrent-voltage measurements. Carrier concentrations obtained from the Raman and UV photocurrent measurements were compared. Strong Raman peaks, comparable in intensity to the LO phonon peak, were observed in the 670 cm<SUP>−1</SUP> to 730 cm<SUP>−1</SUP> wavenumber range, in the frequency gap between the transverse optical (TO) and LO phonon modes of bulk GaN. The peaks in the 670 cm<SUP>−1</SUP> to 730 cm<SUP>−1</SUP> range are ascribed to Frohlich modes localized near the surfaces of the nanowires, or interfaces between the nanowires and unintentional surface adsorbates. Spatially resolved Raman measurements were performed along the radial direction of a 76 mm diameter wafer, from the center to the edge of the wafer, and compared with changes in nanowire growth morphology along the radial direction, which were observed by electron microscopy. The intensity ratio of the Frohlich modes to the LO phonon - plasmon mode was observed to increase from the center to the edge of the wafer. In addition, the E<SUB>2</SUB>(high) Raman peak (at 568 cm<SUP>−1</SUP>) was observed to broaden and shift to lower wavenumber from the center to the edge, which suggests an increase in tensile stress in the material grown near the edge of the wafer. The tensile stress may arise from GaN material with a faceted, non-nanowire morphology, which was observed to grow between the nanowires.