Albert Feldman

Application of the three omega thermal conductivity measurement method to a film on a substrate of finite thickness

The three omega thermal conductivity measurement method is analyzed for the case of one or more thin films on a substrate of finite thickness. The analysis is used to obtain the thermal conductivities of SiO2 films on Si substrates and of a chemical vapor deposition (CVD) diamond plate. For the case of the SiO2 films on a Si, we find an apparent thickness dependence of the thermal conductivity of the SiO2 films. However, the data can also be explained by a thickness-independent thermal conductivity and an interfacial thermal resistance. For the case of the CVD diamond plate, the fit of the theory to the experimental data is significantly improved if we assume that an interface layer separates the heater from the diamond plate.

Thermal and electrical properties of copper‐tin and nickel‐tin intermetallics

The thermal diffusivity, electrical resistivity, density, and heat capacity have been measured for Cu6Sn5, Cu3Sn, and Ni3Sn4. These properties were used to evaluate the apparent Lorenz number for comparison with the theoretical value. Acceptable agreement was found.

Optical and physical parameters of Plexiglas 55 and Lexan

The following parameters have been obtained for Plexiglas 55 and Lexan: refractive index n at 486.1 nm, 589.3 nm, and 656.3 nm, the thermooptic constant dn/dT at 632.8 nm, the linear thermal expansion coefficient; the photoelastic constants q(11), q(12), p(11), and p(12); and the elastic moduli c(11), c(12), s(11), and s(12). The experimental value for the density derivative of refractive index rho(dn/drho)T deviates by only a small amount from the value calculated from the Lorentz-Lorenz equation. This is the expected result for molecular solids. The density variation with temperature is the dominant contribution to dn/dT.

OPTICAL ACTIVITY AND FARADAY ROTATION IN BISMUTH OXIDE COMPOUNDS

The optical rotatory power and Faraday rotation were measured in crystals of 17Bi2O3: Ga2O3, 7Bi2O3: ZnO, Bi12TiO20, Bi12GeO20, and Bi12SiO20 in the wavelength range 400 to 700 nm at room temperature. Our crystals were enantiomorphs of those reported previously. The large Verdet coefficients indicate that these crystals are potentially useful as magneto‐optic modulator materials.

Growth defects in diamond films

Abstract : Growth defects in diamond films grown by plasma-assisted chemical vapor deposition (CVD) were studied by high resolution electron microscopy. Several features of the microstructure were resolved and their importance to the growth of the diamond film was evaluated. The observations included various twin boundaries of the type sigma=3 as well as sigma=9, sigma=27 and sigma=81, which form by an interaction of lower order twins. These higher order boundaries, are loci of intersection points of growing planes on two adjacent twins and can serve as an indicator for the local crystal growth direction. The central nucleation site for the growing planes in many cases can be traced back to a quintuplet twin point. A twin quintuplet has five reentrant angles and thus serves as a preferred nucleation site for new planes as the crystal grows.

Eddy‐current losses due to a surface crack in conducting material

Calculations are reported for the spatial distribution of magnetic fields in the neighborhood of a long surface crack in a conductor, where a uniform ac magnetic field is applied parallel to the length of the crack. The problem is resolved into tractable parts consisting of the cases of eddy currents near a semi‐infinite crack with a sharp tip and eddy currents near a square corner. The semi‐infinite crack problem is solved exactly by a modification of Sommerfeld’s diffraction theory and the corner problem is treated by a Green’s function obtained by the method of images. The composite solution is valid for a crack of depth equal to four times the electromagnetic skin depth or greater. From the solution, the Poynting vector is calculated and its integral over the surface computed. The change in power dissipation relative to the ’’uncracked’’ surface is given in a simple form.

Moire fringe images of twin boundaries in chemical vapor deposited diamond

Features in lattice image micrographs of chemical vapor deposited diamond can be interpreted as Moire fringes that occur when viewing twin boundaries that are inclined to the electron beam. The periodicities in images of inclined twin boundaries with Σ=3 and Σ=9 misorientations have been modeled by computer graphic simulation.

Ultralinear bistable electro‐optic polarization modulator

An optical device utilizing optical feedback has been constructed with a Pockels cell and polarizing components. Two modes of operation of the device are demonstrated. Both modes exhibit optical bistability. It is demonstrated that in one mode of operation the nonlinear dependence of the output intensity as a function of an input optical or electrical signal can be made arbitrarily small compared to the linear dependence.

Refractive Index of Cuprous Chloride

The refractive index of single-crystal CuCl at room temperature was measured in the wavelength range 0.42–1.2 μm using a V-block refractometer. The range of wavelengths was extended to 22 μm by measuring the wavelength dependence of interference fringes in thin polished plates. A dispersion equation was fitted to the data over a limited wavelength range.

X-ray photoelectron spectroscopy of O 1s and Si 2p lines in films of SiOx formed by electron beam evaporation

X-ray photoelectron spectroscopy measurements were made of the line shapes and binding energies of the O 1s and Si 2p lines in films of the SiOx system prepared by electron beam evaporation. Stoichiometries were in the range 0 < x < 2. The spectra contain principally two Si 2p peaks which change in amplitude and move to higher energies in a continuous manner as a function of x. The O 1s peak is a single line which shifts in a non-linear manner as a function of x. The results for films with 0.9 < x < 2 are consistent with a mixture of silicon clusters and silicon-centered tetrahedra deficient in oxygen, silicon-centered tetrahedra conforming to the random bond model (RBM), and forms of oxygen other than bridging oxygen such as peroxy bonding, molecular oxygen or OH. The films with x < 0.9 appear to be composed of silicon clusters and silicon-centered tetrahedra richer in oxygen than would be expected on the basis of the RBM. In these films the non-bridging oxygen content would be greatly diminished.