TY - JOUR
T1 - Anisotropic strain and phonon deformation potentials in GaN
AU - Darakchieva, V.
AU - Paskova, T.
AU - Schubert, M.
AU - Arwin, H.
AU - Paskov, P. P.
AU - Monemar, B.
AU - Hommel, D.
AU - Heuken, M.
AU - Off, J.
AU - Scholz, F.
AU - Haskell, B. A.
AU - Fini, P. T.
AU - Speck, J. S.
AU - Nakamura, S.
PY - 2007/5/29
Y1 - 2007/5/29
N2 - We report optical phonon frequency studies in anisotropically strained c -plane- and a -plane-oriented GaN films by generalized infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The anisotropic strain in the films is obtained from high-resolution x-ray diffraction measurements. Experimental evidence for splitting of the GaN E1 (TO), E1 (LO), and E2 phonons under anisotropic strain in the basal plane is presented, and their phonon deformation potentials c E1 (TO), c E1 (LO), and c E2 are determined. A distinct correlation between anisotropic strain and the A1 (TO) and E1 (LO) frequencies of a -plane GaN films reveals the a A1 (TO), b A1 (TO), a E1 (LO), and b E1 (LO) phonon deformation potentials. The a A1 (TO) and b A1 (TO) are found to be in very good agreement with previous results from Raman experiments. Our a A1 (TO) and a E1 (LO) phonon deformation potentials agree well with recently reported theoretical estimations, while b A1 (TO) and b E1 (LO) are found to be significantly larger than the theoretical values. A discussion of the observed differences is presented.
AB - We report optical phonon frequency studies in anisotropically strained c -plane- and a -plane-oriented GaN films by generalized infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The anisotropic strain in the films is obtained from high-resolution x-ray diffraction measurements. Experimental evidence for splitting of the GaN E1 (TO), E1 (LO), and E2 phonons under anisotropic strain in the basal plane is presented, and their phonon deformation potentials c E1 (TO), c E1 (LO), and c E2 are determined. A distinct correlation between anisotropic strain and the A1 (TO) and E1 (LO) frequencies of a -plane GaN films reveals the a A1 (TO), b A1 (TO), a E1 (LO), and b E1 (LO) phonon deformation potentials. The a A1 (TO) and b A1 (TO) are found to be in very good agreement with previous results from Raman experiments. Our a A1 (TO) and a E1 (LO) phonon deformation potentials agree well with recently reported theoretical estimations, while b A1 (TO) and b E1 (LO) are found to be significantly larger than the theoretical values. A discussion of the observed differences is presented.
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U2 - 10.1103/PhysRevB.75.195217
DO - 10.1103/PhysRevB.75.195217
M3 - Article
AN - SCOPUS:34347359718
VL - 75
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 1098-0121
IS - 19
M1 - 195217
ER -