Elastic properties of β-SiC films by Brillouin light scattering

Abstract

Brillouin light scattering has been used to investigate elastic properties of a monocrystalline and of 〈111〉 textured polycrystalline 3C polytype silicon carbide films that have been deposited on silicon substrate by chemical vapor deposition. Taking advantage from the detection of different acoustic modes, a complete elastic characterization of the films has been achieved. The three unknown elastic constants of the monocrystalline 3C-SiC, namely, c11=395 GPa, (c11−c12)/2=136 GPa, and c44=236 GPa have been selectively determined, respectively, from the frequency of the longitudinal and of the shear horizontal bulk modes traveling parallelly to the film surface. These determinations are in agreement with the frequency of the observed Rayleigh surface mode, of the pseudosurface mode, and of the bulk waves propagating at different angles from the normal of the single crystal film plane and consistent with existing theoretical calculations of β-SiC elastic constants. Finally, the calculated Voigt average values of the effective elastic constants for the 〈111〉 textured 3C-SiC polycrystalline film using the single crystal constants provides a good agreement with our experimental results (C11=500 GPa, C33=535 GPa, C44=165 GPa, C66=210 GPa, and C13=50 GPa) and compare fairly well with the α-SiC published one. These results confirm that the elastic constants of silicon carbide are slightly influenced by the polytypism.