Experimental and theoretical determination of the opto-acoustic spectrum of silicon

Knowledge of the photon energy-dependent photo-elastic (PE) response for a wide range of semiconductors is essential for the development of opto-electronic platforms. Coherent acoustic phonon spectroscopy provides a novel approach to measure depth-dependent optical properties in semiconductor materials with high resolution. Here we report measurements and calculations for bulk silicon in the photon energy range 1.5–3.4 eV. First-principles calculations of the PE spectra show remarkable agreement with the opto-acoustic measurements. These results show promise that this combined experimental and theoretical approach can be effective in characterizing defect induced modification in PE response as a function of depth and defect concentration.