Micro-Raman spectra of a free-standing GaN NW recorded in quasibackscattering geometry for excitation laser power of 0.25 mW near the sample surface. The inset shows a cross-sectional SEM image of as-grown GaN NWs on Si (111) substrate.
Laser power dependent Raman spectra of GaN NW (a) Raman shift of the phonon mode and (b) coupled LO phonon-plasmon mode.
Linewidth and peak positions of and modes as a function of lattice temperature. (a) FWHM of and modes and (b) peak position of and modes.
The electron mobility as a function of laser induced temperature in comparison with data extracted from literature for GaN bulk [31,32] and NWs . The inset shows Raman spectrum of coupled LO phonon-plasmon mode of free-standing GaN NWs for 1 mW (the gray line is the fitting curve by line shape analysis and open circle is the experimental curve).
Micro-Raman spectra of vertically aligned undoped and doped GaN NWs recorded in backscattering geometry for excitation laser power of 3.65 mW. The inset shows a fitting curve for Si doped GaN NWs by line shape analysis.
Typical phonon frequencies and symmetries (for 0.25 mW) observed by Raman scattering for free-standing hexagonal GaN NWs.
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