Brillouin light scattering on chemical-vapor-deposited polycrystalline diamond - evaluation of the elastic moduli

We report on Brillouin light scattering investigations on chemical-vapor-deposited polycrystalline diamond films. Besides the longitudinal and two transverse acoustic bulk phonons, a Rayleigh surface mode is observed. From the bulk modes the elastic constants csub11, csub12, and csub44 of 1062 plus or minus 74, 122 plus or minus 8, and 541 plus or minus 22 GPa, respectively, are determined exhibiting the characteristic values of natural diamond. The observed Rayleigh mode sound velocity of 10326 plus or minus 470 m/s is consistent with the (110) texture of the polycrystalline film and the determined elastic constants.