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  • 1
    Electronic Resource
    Electronic Resource
    Optical constants of GaxIn1−xP lattice matched to GaAs (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3416-3419 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical constants of Ga0.51In0.49P have been determined from 0.8 to 5.0 eV using variable-angle spectroscopic ellipsometry measurements at room temperature. The metal-organic vapor-phase-epitaxy-grown samples were x-ray analyzed to confirm lattice matching to the GaAs substrate. The effects of the native oxide were numerically removed from the data to determine the intrinsic optical constants. This is important because the optical constants reported become generally useful for modeling multiple-layer structures. A Kramers–Kronig analysis was used to reduce interference-related fluctuations in the below-gap refractive index. Near the band edge a mathematical form for excitonic absorption was included. Critical point energies were extracted using a numerical second-derivative fitting algorithm. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358632
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  • 2
    Electronic Resource
    Electronic Resource
    Variable angle spectroscopic ellipsometry: Application to GaAs-AlGaAs multilayer homogeneity characterization (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 5081-5084 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Variable angle spectroscopic ellipsometry has been applied to a GaAs-AlGaAs multilayer structure to obtain a three-dimensional characterization using repetitive measurements at several spots on the same sample. The reproducibility of the layer thickness measurements is of order 10 A(ring), while the lateral dimension is limited by beam diameter, presently of order 1 mm. Thus, the three-dimensional result mainly gives the sample homogeneity. In the present case we used three spots to scan the homogeneity over 1 in. of a wafer, which had molecular-beam epitaxially grown layers. The thickness of the AlGaAs, GaAs, and oxide layers and the Al concentration x varied by 1% or less from edge to edge. This result was confirmed by two methods of data analysis. No evidence of an interfacial layer was observed on top of the AlGaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340406
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  • 3
    Electronic Resource
    Electronic Resource
    Variable angle of incidence spectroscopic ellipsometry: Application to GaAs-AlxGa1−xAs multiple heterostructures (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 3293-3302 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The sensitivity of spectroscopic ellipsometry data to multilayer model parameters is shown to be a strong function of the angle of incidence. A quantitative study of sensitivity versus angle of incidence is performed for a GaAs-AlxGa1−xAs-GaAs substrate structure, showing that maximum sensitivity to layer thicknesses and AlGaAs composition occurs near the wavelength-dependent principal angle. These results are verified by experimental measurements on two molecular-beam epitaxy grown samples. New spectral features, not found in previous ellipsometry studies of similar structures, are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337695
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  • 4
    Electronic Resource
    Electronic Resource
    Ellipsometric measurements of molecular-beam-epitaxy-grown semiconductor multilayer thicknesses: A comparative study (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 4867-4871 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Variable angle of incidence spectroscopic ellipsometry, cross-sectional transmission electron microscopy, and Rutherford backscattering are used to measure heterojunction layer thicknesses in the same AlGaAs/GaAs sample. All three techniques yield the same thickness values within error limits. Two additional samples were implanted with 750-keV Ga ions to fluences of 5×1015 and 1016 cm−2, respectively, and results of diagnostics measurements by the three techniques compared. The three techniques are found to complement each other in providing useful information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338992
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  • 5
    Electronic Resource
    Electronic Resource
    Study of Mo-, Au-, and Ni-implanted molybdenum laser mirrors by multiple angle of incidence spectroscopic ellipsometry (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 779-788 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Multiple angle of incidence spectroscopic ellipsometric data show that implantation of 150-keV molybdenum ions into polished molybdenum laser mirrors causes microscopic surface smoothing, and that most of the microscopic roughness is removed by a fluence of 5×1015 cm−2. Implantation of Au at 1 MeV significantly increases the microscopic roughness, and also changes the bulk optical properties. 3-MeV Ni ion implantation causes only small changes in the surface and bulk properties. A dielectric film, probably a hydrocarbon, is found to condense on the mirrors in a laboratory atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337429
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  • 6
    Electronic Resource
    Electronic Resource
    Temperature dependence of optical properties of GaAs (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 3261-3267 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pseudodielectric functions 〈ε〉=〈ε1〉+i〈ε2〉 of GaAs were measured by spectroscopic ellipsometry (SE), in the range of 1.6–4.45 eV, at temperatures from room temperature (RT) to ∼610 °C. A very clean, smooth surface was obtained by first growing an epitaxial layer of GaAs on a GaAs substrate and immediately capping it with a protective layer of arsenic. The cap prevented surface oxidation during transport to the measurement chamber, where it was evaporated under ultrahigh vacuum at ∼350 °C. Room-temperature SE results from this surface are in good agreement with those in the literature obtained by wet-chemical etching. A quantitative analysis of the 〈ε〉 spectrum was made using the harmonic-oscillator approximation (HOA). It is shown by the HOA that the E1 and E1+Δ1 energy-band critical points shift downward ∼300 meV as temperature increases from RT to ∼610 °C. An algorithm was developed, using the measured optical constants at a number of fixed temperatures, to compute the dielectric function spectrum at an arbitrary temperature in the range of 22–610 °C. Therefore, the ellipsometer can be utilized as an optical thermometer to determine the sample surface temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349285
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  • 7
    Electronic Resource
    Electronic Resource
    Modeling AlxGa1−xAs optical constants as functions of composition (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 5925-5926 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Three models for the dielectric function εx(hν) of AlxGa1−xAs are reviewed. All are based on measured optical constants at discrete compositions. The validity of each model near critical point energies, and otherwise, is evaluated. Only the energy-shift model is appropriate over the entire available spectrum (1.5–6.0 eV), including the band-gap (E0) region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346921
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  • 8
    Electronic Resource
    Electronic Resource
    Optical Characterization of Silicon Oxynitride Thin Films by Variable Angle Spectroscopic Ellipsometry (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 124-128 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Silicon oxynitride (SiOx Ny) thin films were deposited on silicon substrates by ion-assisted deposition. Variable angle spectroscopic ellipsometry (VASE) was used to optically characterize the deposited film properties, such as layer thickness and composition, film surface and interface qualities, as well as the retractive index spectrum in the wavelength range 320-820 nm. The measured VASE spectra were analyzed by assuming SiOx Ny to be a physical mixture of two distinct phases, silicon dioxide and silicon nitride, using the Bruggeman effective medium approximation. Remarkably good agreements between the measured spectra and model calculations were obtained over the entire spectral range for all the samples studied. Layer thicknesses of SiOx Ny films determined by VASE were consistent with their corresponding nominal values. The ellipsometrically deduced refractive index spectrum was observed to be strongly dependent on the film composition. In addition, the film refractive index at each applied wavelength was found to be a linear function of its constituent relative volume fraction. The results from VASE analysis also indicated that all the sample films investigated exhibited smooth surfaces, sharp interfaces between the film and substrate and high packing density.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740180211
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  • 9
    Electronic Resource
    Electronic Resource
    Study of concentration-dependent dielectric properties of n-type GaAs using variable angle spectroscopic ellipsometry (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 107-112 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The dielectric function ε spectra of Si-doped n-type GaAs crystals at room temperature (296 K) have been determined between 1.53 and 5.01 eV, using variable angle spectroscopic ellipsometry (VASE). Samples with carrier concentrations ranging from 4.6 × 1017 to 3.3 × 1018 cm-3 were measured. The effects of surface microscopic roughness, native oxide overlayer and the subsurface damage were mathematically removed with an appropriate multilayer model. The GaAs dielectric function spectra were modeled using the sum of seven harmonic oscillators, whose center energies, half-widths and amplitudes were fitting parameters in the multilayer model. It was found that, as the doping level increased, the E1 and E1 + Δ1 peak structures near 3 eV in the ε2 spectrum broadened considerably more than the E0′ and E2 peak structures near 4.7 eV, while the amplitude of the E1 peak decreased with respect to that of the E1 + Δ1 peak. Other effects due to doping were a shift of the ε2 spectrum towards lower energies and a decrease in the amplitude of the E2 peak.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740180208
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  • 10
    Electronic Resource
    Electronic Resource
    Characterization of polycrystalline silicon thin-film multilayers by variable angle spectroscopic ellipsometry (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 113-118 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Samples of polycrystalline silicon (poly-Si) thin-film multilayers were prepared by low-pressure chemical vapor deposition. Analysis of these samples by cross-sectional transmission electron microscopy (XTEM) revealed large changes in grain size between the undoped-as-deposited and doped-annealed poly-Si layers. Roughness at the top of the poly-Si layers was also observed by XTEM. Non-destructive variable angle spectroscopic ellipsometry (VASE) was used to characterize these structures and to determine the layer thicknesses and compositions. The poly-Si and roughness layers were each modeled as physical mixtures, using the Bruggeman effective medium approximation, and incorporated into the appropriate multilayer fitting models. As a result, layer thicknesses and compositions, as well as the surface and interface roughnesses, were determined. The VASE-obtained thicknesses compared well with those determined by destructive XTEM. The effects on the poly-Si layer microstructure due to doping and annealing were also characterized.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740180209
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