GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    Online Resource
    Online Resource
    Nanocrystal characterization by ellipsometry in porous silicon using model dielectric function
    AIP Publishing ; 2009
    In:  Journal of Applied Physics Vol. 105, No. 2 ( 2009-01-15)
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 105, No. 2 ( 2009-01-15)
    Abstract: Porous silicon layers were prepared by electrochemical etching of p-type single-crystal Si (c-Si) of varying dopant concentration resulting in gradually changing morphology and nanocrystal (wall) sizes in the range of 2–25nm. We used the model dielectric function (MDF) of Adachi to characterize these porous silicon thin films of systematically changing nanocrystal size. In the optical model both the surface and interface roughnesses have to be taken into account, and the E0, E1, and E2 critical point (CP) features are all described by a combination of several lineshapes (two-dimensional CP, excitonic, damped harmonic oscillator). This results in using numerous parameters, so the number of fitted parameters were reduced by parameter coupling and neglecting insensitive parameters. Because of the large number of fitted parameters, cross correlations have to be investigated thoroughly. The broadening parameters of the interband transitions in the measured photon energy range correlate with the long-range order in the crystal. The advantage of this method over the robust and simple effective medium approximation (EMA) using a composition of voids and c-Si with a nanocrystalline Si reference [Petrik et al., Appl. Surf. Sci. 253, 200 (2006)] is that the combined EMA+MDF multilayer method of this work provides a more detailed description of the material and layer structure.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/1.3068479
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2009
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 2
    Online Resource
    Online Resource
    Approaching the high intrinsic electrical resistivity of NbO2 in epitaxially grown films
    AIP Publishing ; 2020
    In:  Applied Physics Letters Vol. 116, No. 18 ( 2020-05-04)
    Details
    In: Applied Physics Letters, AIP Publishing, Vol. 116, No. 18 ( 2020-05-04)
    Abstract: NbO2 is a promising candidate for resistive switching devices due to an insulator-metal transition above room temperature, which is related to a phase transition from a distorted rutile structure to an undistorted one. However, the electrical resistivity of the NbO2 thin films produced so far has been too low to achieve high on-off switching ratios. Here, we report on the structural, electrical, and optical characterization of single-crystalline NbO2 (001) thin films grown by pulsed laser deposition on MgF2 (001) substrates. An annealing step reduced the full width at half maximum of the NbO2 (004) x-ray Bragg reflection by one order of magnitude, while the electrical resistivity of the films increased by two orders of magnitude to about 1 kΩcm at room temperature. Temperature-dependent resistivity measurements of an annealed sample revealed that below 650 K, two deep-level defects with activation energies of 0.25 eV and 0.37 eV dominate the conduction, while above 650 K, intrinsic conduction prevails. Optical characterization by spectroscopic ellipsometry and by absorption measurements with the electric field vector of the incident light perpendicular to the c-axis of the distorted rutile structure indicates the onset of fundamental absorption at about 0.76 eV at room temperature, while at 4 K, the onset shifts to 0.85 eV. These optical transitions are interpreted to take place across the theoretically predicted indirect bandgap of distorted rutile NbO2.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    URL: Article
    DOI: 10.1063/5.0005523
    RVK:
    UA 1000
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2020
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Optical models for ultrathin oxides on Si- and C-terminated faces of thermally oxidized SiC
    AIP Publishing ; 2009
    In:  Journal of Applied Physics Vol. 106, No. 12 ( 2009-12-15)
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 106, No. 12 ( 2009-12-15)
    Abstract: The thickness, refractive index, density, and interface properties of thin thermal oxides on both Si- and C-terminated 4H-SiC faces were investigated by ellipsometry using optical models of increasing complexity. We used different parametrizations of the dielectric function, a transition layer, and also investigated the multisample approach. The thickness of the transition layer increases with decreasing oxide thickness below the layer thickness of about 30nm, it correlates with the surface roughness measured by atomic force microscopy, and it was found to be significantly larger for the C-terminated than that for the Si-terminated face. For oxide layer thicknesses larger than 30nm, the refractive index of the bulk oxide layer is the same as that of thermal SiO2 on Si. We found an apparent decrease in mass density (as well as optical density) with decreasing oxide thickness using a combination of ellipsometry and backscattering spectrometry, which can be explained by the surface roughness, depending on the layer thickness revealed by atomic force microscopy.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/1.3270424
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2009
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 4
    Online Resource
    Online Resource
    Influence of 20 MeV electron irradiation on the optical properties and phase composition of SiOx thin films
    AIP Publishing ; 2018
    In:  Journal of Applied Physics Vol. 123, No. 19 ( 2018-05-21)
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 123, No. 19 ( 2018-05-21)
    Abstract: Homogeneous films from SiO1.3 (250 nm thick) were deposited on crystalline Si substrates by thermal evaporation of silicon monoxide. A part of the films was further annealed at 700 °C to grow amorphous Si (a-Si) nanoclusters in an oxide matrix, thus producing composite a-Si-SiO1.8 films. Homogeneous as well as composite films were irradiated by 20-MeV electrons at fluences of 7.2 × 1014 and 1.44 × 1015 el/cm2. The film thicknesses and optical constants were explored by spectroscopic ellipsometry. The development of the phase composition of the films caused by the electron-beam irradiation was studied by transmission electron microscopy. The ellipsometric and electron microscopy results have shown that the SiOx films are optically homogeneous and the electron irradiation with a fluence of 7.2 × 1014 el/cm2 has led to small changes in the optical constants and the formation of very small a-Si nanoclusters. The irradiation of the a-Si-SiOx composite films caused a decrease in the effective refractive index and, at the same time, an increase in the refractive index of the oxide matrix. Irradiation induced increase in the optical band gap and decrease in the absorption coefficient of the thermally grown amorphous Si nanoclusters have also been observed. The obtained results are discussed in terms of the formation of small amorphous silicon nanoclusters in the homogeneous layers and electron irradiation induced reduction in the nanocluster size in the composite films. The conclusion for the nanoparticle size reduction is supported by infrared transmittance results.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/1.5022651
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2018
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 5
    Online Resource
    Online Resource
    A unique vibrational signature of rotated water monolayers on Pt(111): Predicted and observed
    AIP Publishing ; 2011
    In:  The Journal of Chemical Physics Vol. 134, No. 20 ( 2011-05-28)
    Details
    In: The Journal of Chemical Physics, AIP Publishing, Vol. 134, No. 20 ( 2011-05-28)
    Abstract: Six H-bonds in the periodic di-interstitial structure that accounts for scanning tunneling microscope images of “$\sqrt {37}$37” and “$\sqrt {39}$39” wetting layers on Pt(111) are some 0.2 Å shorter than H-bonds are in ice Ih. According to a broadly obeyed correlation, this density functional theory result implies a stringent test of the di-interstitial motif, namely the presence of an OH-stretch band red-shifted from that of ice Ih by more than 1000 cm−1. Infrared absorption spectra satisfy the test, in showing a feature centered at about 1965 cm−1, which grows in as deposited water orders.
    Type of Medium: Online Resource
    ISSN: 0021-9606 , 1089-7690
    URL: Article
    DOI: 10.1063/1.3591966
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2011
    detail.hit.zdb_id: 3113-6
    detail.hit.zdb_id: 1473050-9
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...