QUANTITATIVE PHONON SPECTROSCOPY OF INTERSTITIAL OXYGEN IN SILICON

By means of phonon spectroscopy with superconducting tunneling junctio ns, resonant phonon scattering by interstitial oxygen in silicon at 87 8 GHz is investigated. The acoustic scattering cross section obtained by comparison of experimental and calculated phonon transmission spect ra is anisotropic with values of 2.4 x 10(-14) cm(2) in [100]-directio n and 5.0 x 10(-14) cm(2) in [111]-direction and used for calibration. The fitting procedure takes into account crystal-related parameters l ike orientation, phonon focusing, multiple phonon scattering as well a s the sample and junction dimensions. By comparing the phonon scatteri ng by the O-18-isotope it is shown that oxygen concentrations of 7 x 1 0(13) cm(-3) can be determined with high accuracy.