  The observation of pure phonon confinement effect in germanium nanowires is
limited due to the illumination sensitivity of Raman spectra. In this paper we
measured Raman spectra for different size germanium nanowires with different
excitation laser powers and wavelengths. By eliminating the local heating
effect, the phonon confinement effect for small size nanowires was clearly
identified. We have also fitted the Raman feature changes to estimate the size
distribution of nanowires for the first time.
