ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (36)
Collection
  • Articles  (36)
Journal
  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial PbTiO3 films were prepared by metalorganic chemical-vapor deposition on MgO(001)-, SrTiO3(001)-, and LaAlO3(001)-oriented substrates. Four-circle x-ray diffraction, transmission electron microscopy, Rutherford backscattering (RBS) channeling, and optical waveguiding were performed to characterize the deposited films. Epitaxial, single-crystal films were obtained on all three substrate materials under the same growth conditions. However, the defect structure of the films, including grain tilting, threading dislocation density, and 90° domain formation, was strongly dependent on the choice of substrate material. Films grown on MgO(001) and LaAlO3(001) (pseudocubic indices) substrates are nominally c-axis oriented; however, the PbTiO3 grains in the film form a fourfold domain structure, with the grains tilted ∼0.6° and ∼0.7°, respectively, toward the [100] directions (cubic or pseudo-cubic) of the substrates. In addition, these films contain a significant volume fraction of 90°-domain (a-axis) structures with a critical thickness hc for domain formation below the detection level of our experiments (hc≥100 A(ring)). Together, these structural defects result in a low RBS channeling yield reduction. In contrast, films grown on SrTiO3(001) substrates showed no tilting of the c-axis grains and a minimum RBS channeling yield of as low as ∼3%. In addition, we observed that below a critical film thickness of hc∼1500 A(ring), 90° domain formation was completely suppressed resulting in a nearly perfect single-crystal structure.The refractive indices and optical birefringence of the films were measured as a function of wavelength using the film-prism coupling method. Both the ordinary and extraordinary refractive indices for films grown on MgO(001) and LaAlO3(001) were higher than that of single-crystal PbTiO3; however, the optical birefringence of films grown on MgO(001) was reduced from that of the bulk. For films grown on SrTiO3(001), the ordinary refractive index was very close to that of single-crystal PbTiO3. We correlate the refractive index values and the reduced birefringence to the degree of residual strain and the volume fraction of 90° domains in the samples, respectively. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 7823-7830 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report optical waveguiding in single-crystal, epitaxial (101) oriented rutile (TiO2) thin films grown on (112¯0) sapphire (α-Al2O3) substrates using the metal-organic chemical vapor deposition technique. The electromagnetic field distributions and propagation constants for asymmetric planar waveguides composed of an anisotropic dielectric media applicable to these films are derived. Modifications to the prism-film coupling theory for this anisotropic case are also discussed. By application of this model to (101) oriented rutile thin films, we directly obtain values of the ordinary and extraordinary refractive indexes, n0 and ne, of the rutile thin films as well as film thicknesses. We obtain typical values of the refractive indexes (n0=2.5701±0.0005; ne=2.934±0.001) near to those for bulk rutile single crystals indicating the exceptional quality of these films.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1405-1415 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental evidence is presented to verify the quantitative predictions of interfacial defect theory as applied to strain relief in epitaxial PbTiO3 thin films through the formation of 90° domains. Epitaxial PbTiO3 thin films grown by metal-organic chemical vapor deposition on MgO(001), SrTiO3(001), LaAlO3(001), and SrRuO3(001)/SrTiO3(001) substrates are examined using four-circle x-ray diffraction and transmission electron microscopy. The data represents a detailed examination of the ...c/a/c/a... 90° domain patterns that develop during the paraelectric to ferroelectric (PE→FE) phase transition as the film is cooled from the growth temperature. Three independent measurements of the relative coherency strain (er) are reported. The data quantitatively and self-consistently verify the crystallographic rotations predicted by the concept of the relative coherency strain and demonstrate the validity of domain stability maps in understanding the phase transformation history in epitaxial ferroelectric thin films. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial thin films of TiO2 and VO2 single layers and TiO2/VO2 multilayers were grown on (112¯0) sapphire (α-Al2O3) substrates using the metalorganic chemical vapor deposition technique and were characterized using Raman scattering and four-circle x-ray diffractometry. X-ray diffraction results indicate that the films are high quality single crystal material with well defined growth plane and small in-plane and out-of-plane mosaic. Single-layer films are shown to obey the Raman selection rules of TiO2 and VO2 single crystals. The close adherence to the Raman selection rules indicates the high degree of orientation of the films, both parallel and perpendicular to the growth plane. Selection rule spectra of two and three layer TiO2/VO2 multilayers are dominated by the VO2 layers with only minimal signature of the TiO2 layers. Due to the low band gap of semiconducting vanadium dioxide, we attribute the strong signature of the VO2 layers to resonant enhancement of the VO2 Raman component accompanied with absorption of the both the incident and scattered laser light from the TiO2 layers.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4481-4486 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Domain switching of 90° ferroelectric domains in tetragonal BaTiO3 and PbTiO3 is induced by the application of stress along specific crystallographic axes. For BaTiO3, single-domain crystals are obtained from twinned specimens by the application of ∼1.1 MPa of stress parallel to the a axis and twin boundaries are induced by application of ∼0.22 MPa of stress parallel to the c axis. Similar piezoelectrically-induced domain switching was observed in PbTiO3 at elevated temperature. We observed the rotation of the crystallographic axes associated with domain switching via micro-Raman spectroscopy. These results were consistent with optical microscope images of the domain switching which demonstrates the usefulness of micro-Raman spectroscopy for the study of ferroelectric domain structures. A phenomenological treatment of domain switching in a piezoelectrically-coupled system is described.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2972-2974 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recent electron diffraction and microscopy studies of GaN nucleation layers have shown that faults in the stacking of the close-packed planes result in the coexistence of cubic and hexagonal phases within the layers. Using grazing incidence x-ray scattering, we have quantified the proportion of the cubic and hexagonal phases throughout the nucleation layer. We compare the structure of a 20 nm nucleation layer grown on sapphire by atmospheric pressure metal-organic chemical vapor deposition at 525 °C to that of an identical layer heated to 1060 °C. The fractions of cubic and hexagonal phases in the layers are determined by a comparison of the scattering data with a Hendricks–Teller model. High temperature exposure results in a decrease of the cubic fraction from 0.56 to 0.17. The good agreement with the Hendricks–Teller model indicates that the positions of the stacking faults are uncorrelated. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single-crystal thin films of Pb(ZrxTi1−x)O3 (PZT) covering the full compositional range (0≤x≤1) were deposited by metal-organic chemical vapor deposition. Epitaxial SrRuO3(001) thin films grown on SrTiO3(001) substrates by rf-magnetron sputter deposition served as template electrode layers to promote the epitaxial growth of PZT. X-ray diffraction, energy-dispersive x-ray spectroscopy, atomic force microscopy, transmission electron microscopy, and optical waveguiding were used to characterize the crystalline structure, composition, surface morphology, microstructure, refractive index, and film thickness of the deposited films. The PZT films were single crystalline for all compositions exhibiting cube-on-cube growth epitaxy with the substrate and showed very high degrees of crystallinity and orientation. The films exhibited typical root mean square surface roughness of ∼1.0–2.5 nm. For tetragonal films, the surface morphology was dominated by grain tilting resulting from ferroelectric domain formation. We report the systematic compositional variation of the optical, dielectric, polarization, and electronic transport properties of these single-crystalline PZT thin films. We show that the solid-solution phase diagram of the PZT system for thin films differs from the bulk due to epitaxy-induced strains and interfacial defect formation. High values of remanant polarization (30–55 μC/cm2) were observed for ferroelectric compositions in the range of 0.8≤x≤0.2. Unlike previous studies, the dielectric constant exhibited a clear dependence on composition with values ranging from 225 to 650. The coercive fields decreased with increasing Zr concentration to a minimum of 20 kV/cm for x=0.8. The undoped films exhibited both high resistivity and dielectric-breakdown strength (1013–1014 Ω cm at 100 kV/cm and 300–700 kV/cm, respectively). © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 790-790 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1106-1108 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single-crystal films of PbTiO3 have been deposited on (100) SrTiO3 substrates by metalorganic chemical vapor deposition. X-ray diffraction spectra and transmission electron microscopy images revealed that the development of 90° domains was directly related to the thickness of the film. Single-domain, single-crystal films were obtained for film thickness less than 150 nm. The minimum yields of the films in ion-channeling experiments were only 3 %, similar to that of a perfect single crystal. The ordinary refractive index of the film measured by optical waveguiding experiment was also the same as that of PbTiO3 single crystals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1572-1574 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Highly oriented, polycrystalline Pb(Zr0.5Ti0.5)O3 (PZT) thin films were successfully grown on RuO2/SiO2/(001)Si using metal–organic chemical vapor deposition (MOCVD) at 525 °C. The orientation of the PZT film was controlled by using MOCVD-deposited highly textured RuO2 bottom electrodes. A (001)-oriented PZT film was observed for growth on (101)-textured RuO2. In contrast, for (110) RuO2, the growth of (001) PZT was greatly suppressed while the growth of both (110) and (111) were enhanced, resulting in a poorly (001)-textured polycrystalline film. The as-grown PZT films exhibited a dense columnar microstructure with an average grain size of 150–250 nm. Both PZT films showed excellent ferroelectric properties without any postgrowth annealing. The (001) highly oriented PZT films showed significantly higher values of remnant polarization (Pr=49.7 μC/cm2) and saturation polarization (Ps=82.5 μC/cm2). In comparison, for the PZT films grown on (110) RuO2, Pr and Ps were 21.5 and 35.4 μC/cm2, respectively. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...