Elastic Waves in Nano-Columnar Porous 4H-SiC Measured by Brillouin Scattering

We report measured and calculated frequencies of elastic waves propagating in columnar porous 4H-SiC, an analytically tractable system. The sample was prepared using photo-electrochemical etching followed by mechanical polishing. The frequencies were measured using Brillouin scattering spectroscopy in backscattering geometry. The effective elastic constants, ordinary and extraordinary indices of refraction, and mass density, all obtained using effective medium models, are used to calculate the frequencies. Although the quasistatic limit is not strongly satisfied, the agreement between the measured and calculated values is good.