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138 results on '"Wolfe, J. C."'

4. Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

Author

Wosik, J, Kranenburg, R. A, Wolfe, J. C, Selvamanickam, V, and Salama, K

Subjects
Solid-State Physics
Abstract

Measurements of the millimeter wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid phase process are reported. The measurements were performed by replacing the endplate of a TE011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. It is shown that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 milliohms. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K, and the surface resistance is less than 50 milliohms at 88 K. The effect of microstructure on surface resistance is discussed.

Published
1991
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5. Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

Author

Wosik, J, Kranenburg, R. A, Wolfe, J. C, Selvamanickam, V, and Salama, K

Subjects
Solid-State Physics
Abstract

Measurements are reported of the millimeter-wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid-phase process. The measurements were performed by replacing the endplate of a TE(011) cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. For the parallel configuration, the surface resistance at 77 K and 80 GHz is given. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K and the surface resistance is derived at 88 K. The effect of microstructure on surface resistance is discussed.

Published
1990

6. Dependence of millimeter wave surface resistance on the deposition parameters of laser ablated YBa2Cu3O(x) thin films

Author

Wosik, J, Robin, T, Davis, M, Wolfe, J. C, Forster, K, Deshmukh, S, Bensaoula, A, Sega, R, Economou, D, and Ignatiev, A

Subjects
Solid-State Physics
Abstract

Measurements of millimeter-wave surface resistance versus temperature have been performed for YBa2Cu3O(x) thin films on 100 line-type SrTiO(3) substrates using a TE(011) cylindrical copper cavity at 80 GHz. The 0.6-micron thick films were grown at several deposition temperatures in the range 690 C to 810 C by means of a pulsed excimer laser ablation technique. A surface resistance minimum (60 milliohm at 77 K) near 770 C is shown to correlate with a minimum in c-axis lattice parameter (11.72 A). The highest value of Tc also occurs near this temperature. The surface resistance of films deposited at 790 C on 110 line-type LaAlO3 subtrates is lower, reaching 8 milliohm at 98 GHz and 80 K, demonstrating the influence of substate material on film quality.

Published
1990

7. Deposition of high quality YBa2Cu3O7-δ thin films over large areas by pulsed laser ablation with substrate scanning.

Author

Davis, M. F., Wosik, J., Forster, K., Deshmukh, S. C., Rampersad, H. R., Shah, S., Siemsen, P., Wolfe, J. C., and Economou, D. J.

Subjects
THIN films, YTTRIUM, BARIUM, COPPER, LASER ablation
Abstract

Presents a study which examined the transport and structural properties of ytrrium barium[sub2]copper[sub3]oxygen[sub7-δ] thin films deposited by pulsed laser ablation. Experimental details; Results and discussion; Conclusion.

Published
1991
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8. Electron beam flash evaporation for YBaCuO and BiCaSrCuO thin films.

Author

Davis, Matthew F., Wosik, Jaroslaw L., and Wolfe, J. C.

Subjects
ELECTRON beams, THIN films, SUPERCONDUCTORS
Abstract

Focuses on a study which described an electron beam flash evaporation technique for superconducting thin films. Information on the superconducting thin films; Methodology of the study; Results and discussion.

Published
1989
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13. Resolution limits of ion milling for fabricating Y1Ba2Cu3Ox nanostructures.

Author

Fong, F-O., Deshmukh, S. C., Davis, M. F., Stumbo, D. P., Wolfe, J. C., and Economou, D. J.

Subjects
NANOSTRUCTURES, SUPERCONDUCTORS, LITHOGRAPHY
Abstract

Focuses on a study which described a process for fabricating high-resolution superconducting nanostructures. Importance of the fabrication of high-resolution superconducting structures; Definition of lithographic patterns; Summary of findings.

Published
1992
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16. Microwave microstrip resonator measurements of Y1Ba2Cu3O(7-x) and Bi2Sr2Ca1Cu2O(8-y) thin films

Author

Lichtenberg, Christopher L, Wosik, Jaroslaw, Davis, Matthew, and Wolfe, J. C

Subjects
Electronics And Electrical Engineering
Abstract

Radio frequency (RF) surface resistance measurement experiments on high T(sub c) thin films were performed. The method uses a microstrip resonator comprising a top gold conductor strip, an alumina dielectric layer, and a separate superconductivity ground plane. The surface resistance of the superconducting ground plane can be determined, with reference to a gold calibration standard, from the measured quality factor of the half-wave resonator. Initial results near 7 GHz over the temperature range from 25 to 300 K are presented for YBa2Cu3O(7-x) and Bi2Sr2CaCu2O(8-y) thin film samples deposited by an electron beam flash evaporation process. The RF surface resistance at 25 K for both materials in these samples was found to be near 25 milliohms.

Published
1989

31. Directly sputtered stress-compensated carbon protective layer for silicon stencil masks

Author

Hudek, P., primary, Hrkút, P., additional, Držik, M., additional, Kostič, I., additional, Belov, M., additional, Torres, J., additional, Wasson, J., additional, Wolfe, J. C., additional, Degen, A., additional, Rangelow, I. W., additional, Voigt, J., additional, Butschke, J., additional, Letzkus, F., additional, Springer, R., additional, Ehrmann, A., additional, Kaesmaier, R., additional, Kragler, K., additional, Mathuni, J., additional, Haugeneder, E., additional, and Löschner, H., additional

Published
1999
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37. Novel electrostatic column for ion projection lithography

Author

Chalupka, A., primary, Stengl, G., additional, Buschbeck, H., additional, Lammer, G., additional, Vonach, H., additional, Fischer, R., additional, Hammel, E., additional, Löschner, H., additional, Nowak, R., additional, Wolf, P., additional, Finkelstein, W., additional, Hill, R. W., additional, Berry, I. L., additional, Harriott, L. R., additional, Melngailis, J., additional, Randall, J. N., additional, Wolfe, J. C., additional, Stroh, H., additional, Wollnik, H., additional, Mondelli, A. A., additional, Petillo, J. J., additional, and Leung, K., additional

Published
1994
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46. Photoresist removal using an O2/N2 medium pressure plasma jet with high speed wafer scanning: Unimplanted resist studies.

Author

Bhargava, M., Craver, B., Torres, Jose L., Guo, H., Vemula, S. C., Srivastava, A. K., Berry, I., and Wolfe, J. C.

Subjects
PHOTORESISTS, PLASMA jets, SEMICONDUCTOR wafers, SEMICONDUCTORS, MICROELECTRONICS
Abstract

The authors describe a plasma ashing system where a stationary jet of hot, activated gases removes photoresist from a scanning wafer. The jet is created by a reactant stream flowing through a 2.45 GHz surface wave discharge in a 6 mm quartz tube. For O2/N2 plasmas in the medium pressure range from 20 to 100 Torr, a luminous plasma jet emerges from the end of the discharge tube that transports both heat and reactive species to the wafer. A single scan results in a Gaussian track profile with a standard deviation of 7 mm for the source-to-substrate distance of 9 mm. A simple model of the ashing process, which assumes a thermally activated ash rate and Gaussian distributions for both power density and reactant flux, unifies the dependence of effective ash rate on the substrate temperature and scan speed at a constant power. The best fit activation energy at 2.5 kW is 0.23 eV, about half of the value found in conventional downstream ashing, implying that diffusion plays a significant role in limiting the ash rate. The peak thermal power density in a 2.5 kW jet at 80 Torr is 160 W/cm2, resulting in an effective instantaneous ash rate of 2.5 mm/min for a scan speed of 70 cm/s and 200 °C chuck temperature. This implies that the time to clear a 1.2 μm thick resist coating from a 300 mm wafer is 18 s. [ABSTRACT FROM AUTHOR]

Published
2009
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49. Bragg diffraction, synchrotron x-ray reflectance, and x-ray photoelectron spectroscopy studies of low temperature plasma oxidation of native SiO2 on silicon on insulator.

Author

Bhargava, M., Donner, W., Srivastava, A. K., and Wolfe, J. C.

Subjects
OPTICAL diffraction, X-ray diffraction, SPECTRUM analysis, SILICON, OSCILLATIONS
Abstract

The authors present the application of synchrotron Bragg diffraction, x-ray reflectance (XRR), and x-ray photoelectron spectroscopy (XPS) to study silicon loss in the low temperature plasma oxidation of silicon-on-insulator (SOI) wafers. The Laue oscillations of the Si(004) Bragg peak provide a direct measure of the number of lattice planes that are consumed in the silicon device layer during processing, while the Fourier transform of the XRR data provides a model-independent determination of the increase in the combined thickness of the silicon and surface oxide. XPS measurements provide complementary information concerning changes in thickness, chemical composition, and the bonding of the surface oxide. These methods were applied to samples processed in an oxidizing plasma system at temperatures below 250 °C. The authors find that 2.7±1 Å of silicon, corresponding to two lattice planes, is consumed while the combined thickness increases by 2.7±0.8 Å, corresponding to a net increase in the oxide thickness of 5.4±1.3 Å. Thus, the ratio of oxide growth to silicon loss is about 2.0±0.9, somewhat lower than the bulk ratio of 2.2, but within experimental error. The XPS measurements show the increase to be 5.5 Å. Additionally, XPS shows clearly the consumption of silicon to form Si2O and SiO2 and the net oxidation of Si2O3 to SiO2. [ABSTRACT FROM AUTHOR]

Published
2008
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