Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
82 (1997), S. 1305-1309
ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Raman spectroscopy is used to analyze the effect of electrons on the lattice dynamics of unintentionally heavily doped GaN. The deposition temperature of GaN buffer layers on sapphire substrates is found to have an important influence on the presence of free carriers in GaN layers, evidenced by plasmon coupling to the A1(LO) phonon. Data from infrared measurements are used to calculate the Raman line shape of q=0 coupled A1(LO)-plasmon modes in a dielectric approach and give a good fit of the L−(q=0) component observed in Raman spectra. In particular, the fitting procedure applied to spatially resolved micro-Raman measurements reveals an inhomogeneous concentration of electrons on the scale of hexagonal microcrystallites. Partial screening of phonons with wave vectors differing from the q=0 transfer of incident and scattered photons is invoked to explain LO-like scattering over the whole spectral range of optical phonons, attributed to charge density fluctuations on account of its polarization properties. © 1997 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.365903
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