Phonons in Hexagonal InN. Experiment and Theory

Abstract

We present the results of a detailed study of the first- and second-order Raman scattering and IR reflection from hexagonal InN layers grown on (0001) and (11-02) sapphire substrates. All six Raman active optical phonons were measured and assigned: E2(low) at 87 cm—1, E2(high) at 488 cm—1, A1(TO) at 447 cm—1, E1(TO) at 476 cm—1, A1(LO) at 586 cm—1, and E1(LO) at 593 cm—1. The static dielectric constants of InN for the ordinary and extraordinary directions were estimated to be ε⊥0 = 13.1 and ε∥0 = 14.4, respectively. The phonon dispersion curves and phonon density-of-state function for hexagonal InN were calculated by scanning throughout the BZ.