Quenching of the E2 phonon line in the Raman spectra of wurtzite GaAs nanowires caused by the dielectric polarization contrast.

We investigate the Raman intensity of E₂^H phonons in wurtzite GaAs nanowire ensembles as well as single nanowires as a function of excitation wavelength. For nanowires with radii in the range of 25 nm, an almost complete quenching of the E₂^H phonon line is observed for excitation wavelengths larger than 600 nm. The observed behavior is quantitatively explained by the dielectric polarization contrast for the coupling of light into the GaAs nanowires. Our results define the limits of Raman spectroscopy for the detection of the wurtzite phase in semiconductor nanowires. [ABSTRACT FROM AUTHOR]