On the mixed nature of the 740 cm(-1) band in wurtzite GaN films: A polarized Raman scattering investigation

A detailed study of the polarized Raman scattering of wurtzite GaN films is presented, focusing on the nature of the band centered at 740 cm(-1) observed in the X(Z, Z)X configuration. The origin of this band is ascribed to the mixed contribution of the A I and E, longitudinal phonon modes coupled with the free carrier excitation. The spectral profile of the 740 cm-1 Raman band has been successfully reconstructed through a linear combination of the A(1)-E-1 longitudinal phonon plasmon-coupled modes, leading to a free carrier concentration in good agreement with Hall effect measurements.