Showing papers on "Ellipsometry published in 1970"
TL;DR: In this article, the authors present the results of reflectivity, transmission, and ellipsometry measurements of the absorption edge and the fundamental absorption region of amorphous Ge, Si and GeSi alloys.
Abstract: We present the results of reflectivity, transmission, and ellipsometry measurements of the absorption edge and the fundamental absorption region of amorphous Ge, Si and GeSi alloys. Both the absorption edge and fundamental absorption band shift smoothly from those of Ge to those of Si as the Si concentration increases, in a fashion similar to that of the crystalline alloys. The compositional disorder does not produce any additional energy broadening.
57 citations
TL;DR: In this article, a method for determining substrate optical constants, surface film thickness, and surface film optical constants has been devised by measuring the ellipsometer angles Δ and ψ at several angles of incidence.
Abstract: A method for determining substrate optical constants, surface film thickness, and surface film optical constants has been devised by measuring the ellipsometer angles Δ and ψ at several angles of incidence. This method, previously reported as impossible, solves in a simple fashion the ellipsometry equations for one consistent values of surface film thickness in association with compatible values of substrate optical constants. The technique is advantageous in that vacuum ellipsometry is eliminated and previously unmeasured materials such as alloy structures may be studied readily. Data on aluminum, molybdenum, and silicon are presented illustrating the technique.
41 citations
TL;DR: In this article, a method for computing optical properties of surfaces with a sparse distribution of submicroscopic bumps, pits, or foreign particles on or imbedded in them is described.
Abstract: A method is described for computing optical properties of surfaces with a sparse distribution of submicroscopic bumps, pits, or foreign particles on or imbedded in them. The particles are assumed to be approximate figures of revolution about an axis normal to the surface. Surface and particle are assumed to have uniform, isotropic values of refractive index. Such foreign particles or roughness are equivalent in optical properties to a thin flat film of uniaxial material with its optic axis normal to the surface. The thickness of the equivalent film is arbitrarily made equal to the volume per unit area of all particles or bumps or pits. The principal values of refractive index of this equivalent film are determined by the shape of the particles and any surface irregularity associated with them, and by the refractive indices of particles and substrate, but not by particle size if size is small compared to wavelength of incident radiation. A recent experimental observation that silver tarnish in the form of isolated particles on a flat substrate gives about the same ellipsometric perturbation as would be expected from a flat film of the same refractive index and density appears to be only a rough approximation. Even that approximation would fail if the substrate were not metallic or if the tarnish particles were embedded in the surface. Differences of optical constants derived from measurements on thick and very thin films are explained.
37 citations
TL;DR: In employing ellipsometry to determine the complex refractive index of a reflecting surface, a small systematic error in the zero-angle positions of the polarizers is shown under certain circumstances to have a large effect on the values of the optical constants calculated.
Abstract: In employing ellipsometry to determine the complex refractive index of a reflecting surface, a small systematic error in the zero-angle positions of the polarizers is shown under certain circumstances to have a large effect on the values of the optical constants calculated. The effect of superficial optical anisotropy on ellipsometry in general, and on the zero position determination in particular, is analyzed and a test for the presence of such anisotropy presented.
33 citations
TL;DR: In this article, the plasma anodization of tantalum and niobium in an oxygen d−c glow discharge was confirmed to be analogous to anodisation in aqueous solutions in that evidence was obtained that the ion current in the oxide was a function of field E in the oxides.
Abstract: The plasma anodization of tantalum and niobium in an oxygen d‐c glow discharge was confirmed to be analogous to anodization in aqueous solutions in that evidence was obtained that the ion current in the oxide was a function of field E in the oxide Experimental data on were obtained using in situ ellipsometry to determine the thickness of oxide , and hence (using probe measurements to obtain the potential difference across the oxide) and from The ellipsometry data are consistent with a two‐layer oxide, and this may indicate that both metal and oxygen ion motion is involved in the growth process
33 citations
TL;DR: In this paper, the exact ellipsometry equations including polarizer ellipticity were derived with numerical examples, and a procedure for instrument calibration was described, and experimental results using this procedure were presented.
21 citations
TL;DR: In this article, the intensity of light reflected from SiO2•coated Si, compared with that reflected from the bare Si substrate, may be used for a SiO 2 thickness measurement in the range below 1000 A where conventional methods are difficult to apply.
Abstract: Measurement of the intensity of light reflected from SiO2‐coated Si, compared with that reflected from the bare Si substrate, may be used for a SiO2 thickness measurement in the range below 1000 A where conventional methods are difficult to apply. By going into the ultraviolet much improved sensitivity is obtained, and at 200 nm an 18 A film of SiO2 can be detected. Relative reflectance curves for 589, 400, 300, and 200 nm derived from optical theory are presented; thicknesses measured using these curves are in good agreement with those from ellipsometry. The only apparatus required is a commercially available uv‐vis spectrophotometer equipped with a microbeam reflectance attachment operating at near‐normal incidence. Thickness measurement requires a spot 1–2 mm in diameter and is simple, rapid, and nondestructive.
19 citations
TL;DR: In this paper, the authors review the interpretation of optical reflection techniques in the study of metals and semiconductors in contact with electrolytes, and demonstrate the fact that all of these features may make comparable contributions to optical measurements for the system mercury + aqueous sodium fluoride, and the predicted contributions are compared with experimental results.
Abstract: The improving sensitivity and increasing use of optical reflection techniques in the study of metals and semiconductors in contact with electrolytes, makes it timely to review the interpretation of such measurements. The surface charge on the conductor, the layer of solvent molecules forming the compact layer, the adsorption of ions on the electrode as well as the distribution of ions in the diffuse layer, are all features of the electrical double layer which can contribute to optical measurements. Models of these features are described which facilitate computation of their optical effects, and specimen results are presented. The fact that all of these features may make comparable contributions to optical measurements is illustrated for the system mercury + aqueous sodium fluoride, and the predicted contributions are compared with experimental results.
17 citations
17 citations
16 citations
TL;DR: In this paper, the optical constants n and k were given for thin aluminium films which were deposited in vacuum at a pressure ∼ 1 × 10−9 torr on glass substrates held at 25°c or -196°c.
Abstract: The optical constants n and k are given for thin aluminium films which were deposited in vacuum at a pressure ∼ 1 × 10−9 torr on glass substrates held at 25°c or –196°c. The measurements were made in situ st light wavelengths 5490 A and 5461 A using an ellipsometer. All films showed some degree of preferred orientation. Several films were subjected to a detailed x-ray line profile analysis. The optical constants given for opaque films are higher than values previously reported in the literature. The effect of vacuum annealing at 230°c was also studied. The optical constants of opaque films showed little change in contrast to thinner films for which marked changes in n and k were observed on annealing. A decrease in k was observed for thin films irrespective of substrate deposition temperature. A film deposited at 25°c showed a decrease in n. A film deposited at – 196°c showed an increase in n. An increase in n is attributed to an increase of defect concentration. A combination of x-ray and optica...
01 Jan 1970
TL;DR: In this paper, the application of ellipsometry to the study of the adsorption of polymers at interfaces is discussed and the correction of certain instrumental errors such as imperfect components and the use of solutions containing optically active materials are described.
Abstract: The application of ellipsometry to the study of the adsorption of polymers at interfaces is discussed. The correction of certain instrumental errors such as imperfect components and the use of solutions containing optically active materials are described. Results for the measurement of the extension of polystyrene, poly(ethylene o-phthalate), and certain proteins present in blood adsorbed on surfaces are given and interpreted in terms of changes in molecular conformation that occur during the adsorption process. The differences observed are ascribed to the interaction energies between the different polymers and surfaces.
TL;DR: In this paper, an isolated monolayer is treated fully quantum mechanically, and its effect on the polarization of both a reflected beam and a transmitted beam is calculated and expressed in terms of a "monolayer operator" and a "transmission operator".
TL;DR: In this article, an expression for the optical constants of a rough surface is derived assuming that the slopes of plane facets forming a continuous surface are normally distributed, and assuming that they are smooth.
Abstract: Assuming that the slopes of plane facets forming a continuous surface are normally distributed, an expression is derived for the optical constants of a rough surface.
TL;DR: The change in the polarization state of the light reflected from a rough surface has been studied by considering the reflection from facets inclined at an angle other than zero with the plane of incidence as discussed by the authors.
TL;DR: The constant reflectivity method for determining optical parameters of a system of an isotropic nonabsorbing film on an absorbing substrate using ellipsometry is examined in this paper, and it is shown that this technique can only be considered for either very high or very low ratios of substrate extinction coefficient to substrate refractive index and even then caution must be exercised.