Experimental determination of strain-free Raman frequencies and deformation potentials for the E_2 high and A_1(LO) modes in hexagonal InN

摘要

Strain-free Raman frequencies of the E_2 high and A_1(LO) modes of hexagonal InN are determined to be 490.1±0.2 and 585.4±0.4 cm~(-1) by Raman measurements on a freestanding InN film grown by molecular beam epitaxy. The strain-free Raman frequencies are further confirmed by linear fits to Raman frequencies of the E_2 and A_1(LO) modes of InN epilayers under different biaxial strains. Raman linear biaxial stress coefficients for the E_2 and A_1(LO) modes of InN are obtained with values of 9.0±0.8 and 8.4±0.8 cm~(-1)/GPa. The phonon deformation potentials are also obtained by using sets of available stiffness constants of hexagonal InN.