Browsing by Author "Sauncy, T."

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    Effect of pressure on a defect-related band-resonant vibrational mode in implanation-disordered GaAs
    Sauncy, T.; Holtz, M.; Zallen, Richard H. (American Physical Society, 1994-10)
    We have used hydrostatic pressure as a means for studying a resonant Raman mode observed at 47 cm(-1) in highly disordered, ion implanted, unannealed GaAs. The mode shifts weakly (-0.07 +/- 0.15 cm(-1)/GPa), supporting an identification of this band-resonant vibration as stemming from the breathing mode of the gallium vacancies, which are expected to be in high concentration. We measure a pressure coefficient of the longitudinal-optic phonon in these (5.5 nm) nanocrystals of GaAs to be 3.6 +/- 0.1 cm(-1)/GPa. The good agreement between our value and the pressure shift of this phonon in bulk GaAs implies that the bulk modulus is independent of size at least down to this size crystallite.
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    Effect of pressure on defect-related emission in heavily silicon-doped GaAs
    Holtz, M.; Sauncy, T.; Dallas, T.; Massie, S. (American Physical Society, 1994-11)
    We report cryogenic high-pressure measurements of a defect-related emission at 1.25 eV in silicon-doped GaAs. The pressure measurements prove that the 1.25-eV photon energy is relative to the conduction band, implying a deep defect level 0.30 eV above the valence band and an electron-capture process from the conduction band into the defect. The defect level moves up in the band gap at a rate of 23±3 meV/GPa. These results are consistent with a vacancy-related defect level, possibly stemming from a gallium-vacancy–silicon-at-gallium (second-nearest-neighbor) defect complex.