Phonons in GaN Layers under Anisotropic Strain

GaN layers with vicinal surfaces, such as a-plane surface orientations, reveal all information on their IR active phonon modes upon application of GIRSE. Valuable information on the complete dielectric tensor anisotropy and Ai(TO) phonons in GaN, that is otherwise obscured for c-plane-oriented films, is retrieved. The capability of the GIRSE technique to detect spectrally narrow dichroism in nonpolar GaN films under anisotropic strain, thereby allowing to precisely locate the phonon mode resonances for different polarizations, has been demonstrated. As a result, splittings of the GaN i(TO) and i(LO) phonon modes under anisotropic strain have been identified, further splitting of the GaN 2 phonons measured by Raman spectroscopy has been also demonstrated. 

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