Now showing items 1-14 of 14

    • 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 ...
    • Ferroelastic phase in SrBi2Ta2O9 and study of the ferroelectric phase-transition dynamics 

      Kamba, S.; Pokorny, J.; Porokhonskyy, V.; Petzelt, J.; Moret, M. P.; Garg, A.; Barber, Z. H.; Zallen, Richard H. (AIP Publishing, 2002-08)
      Polarized microscope observation of ferroelastic domains in a SrBi2Ta2O9 (SBT) single crystal reveals the presence of domains up to T(c1)similar or equal to770 K, which supports the ferroelasticity and Amam symmetry of the ...
    • Infrared activity in elemental crystals 

      Zallen, Richard H.; Martin, R. M.; Natoli, V. (American Physical Society, 1994-03)
      In a previous paper, Zallen [Phys. Rev. 173, 824 (1968)] reported a group-theoretical analysis of the competition between unit-cell complexity and crystal symmetry in determining the presence or absence of infrared-active ...
    • Infrared activity in the Aurivillius layered ferroelectric SrBi2Ta2O9 

      Moret, M. P.; Zallen, Richard H.; Newnham, R. E.; Joshi, Pooran C.; Desu, Seshu B. (American Physical Society, 1998-03-01)
      Experimental studies were carried out on infrared-active phonons in the Aurivillius ferroelectric SrBi2Ta2O9 (SBT), using reflectivity measurements (down to 200 cm(-1)) and transmission measurements (down to 100 cm(-1)) ...
    • Infrared reflectivity and lattice fundamentals in anatase TiO2 

      Gonzalez, R. J.; Zallen, Richard H.; Berger, H. (American Physical Society, 1997-03-15)
      Polarization-dependent far-infrared reflectivity measurements were carried out on single crystals of anatase TiO2. The results were analyzed to yield the dielectric dispersion properties of anatase in the lattice fundamentals ...
    • Infrared studies of hole-plasmon excitations in heavily-doped p-type MBE-grown GaAs : C 

      Songprakob, W.; Zallen, Richard H.; Liu, W. K.; Bacher, K. L. (American Physical Society, 2000-08-15)
      Infrared reflectivity measurements (200-5000 cm(-1)) and transmittance measurements (500-5000 cm(-1)) have been carried out on heavily-doped GaAs:C films grown by molecular-beam epitaxy. With increasing carbon concentration, ...
    • Intervalenceband and plasmon optical absorption in heavily doped GaAs:C 

      Songprakob, Wantana; Zallen, Richard H.; Tsu, D. V.; Liu, W. K. (American Institute of Physics, 2002-01-01)
      By using direct numerical-solution techniques for the reflectance (R) and transmittance (T) equations of a multilayer structure, we have analyzed infrared R and T measurements on heavily doped p-type GaAs:C films grown by ...
    • Optical properties of ion-implanted GaAs: The observation of finite-size effects in GaAs microcrystals 

      Feng, G. F.; Zallen, Richard H. (American Physical Society, 1989-07)
      We have carried out reflectivity measurements, for photon energies from 2.0 to 5.6 eV in the electronic interband regime, for a series of unannealed ion-implanted GaAs samples which had been exposed to 45-keV Be+ ions at ...
    • Raman studies of sol-gel alumina - finite-size effects in nanocrystalline ALO(OH) 

      Doss, C. J.; Zallen, Richard H. (American Physical Society, 1993-12-01)
      A systematic Raman-scattering investigation has been carried out on sol-gel alumina prepared by the hot-water hydrolysis and condensation of AI(OC4H9)3, the Yoldas process, as a function of process variables such as the ...
    • Raman-scattering and optical studies of argon-etched GaAs surfaces 

      Feng, G. F.; Zallen, Richard H.; Epp, J. M.; Dillard, J. G. (American Physical Society, 1991-04)
      We have studied the structual damage in low-energy argon-ion-bombarded (ion-etched) GaAs using Raman scattering and ultraviolet reflectivity. When combined with post-bombardment sequential chemical etching, the Raman results ...
    • Raman-scattering depth profile of the structure of ion-implanted GaAs 

      Holtz, M.; Zallen, Richard H.; Brafman, O.; Matteson, S. (American Physical Society, 1988-03)
      We have carried out an extensive Raman-scattering investigation of the structure of beryllium-implanted gallium arsenide. Single-crystal GaAs was bombarded with 45-keV Be+ ions, and backscattering Raman measurements were ...
    • Raman_scattering studies of silicon_implanted gallium arsenide: The role of amorphicity 

      Holtz, Mark; Zallen, Richard H.; Geissberger, Art E.; Sadler, R. A. (American Institute of Physics, 1986-03-15)
      A series of Raman_scattering experiments were carried out on GaAsimplanted with Si+ and with SiF+ 3 ions, both before and after annealing, for samples subjected to fluences spanning a wide range. The implantation_induced ...
    • Resonant Raman-active acoustic phonons in ion-implanted GaAs 

      Holtz, M.; Zallen, Richard H.; Brafman, O. (American Physical Society, 1988-09)
      We have observed a new, strong feature at 47 cm-1 in the first-order Raman spectrum of ion-implanted GaAs, prior to any anneal. It is not present in the Raman spectrum of either amorphous or single-crystal GaAs. The peak ...
    • Resonant Raman-active acoustic phonons in the mixed amorphous-microcrystalline phase of ion-implanted GaAs 

      Holtz, M.; Zallen, Richard H.; Brafman, O. (American Physical Society, 1988-02)
      We have observed a new, strong, low-frequency peak (at 47 cm-1) in the Raman spectrum of ion-implanted GaAs having a mixed amorphous-microcrystalline microstructure. It is strongly resonant near 1.7 eV, just above the band ...