NASA Scientific and Technical Aerospace Reports

20040112016 NASA Glenn Research Center, Cleveland, OH, USA
Excitation of Coupled Slotline Mode in Finite Ground CPW with Unequal Ground Plane Widths
Ponchak, George E.; Papapolymerou, John; Tentzeris, Manos M.; [2004]; 5 pp.; In English; Copyright; Avail: CASI; A01,
Hardcopy
The coupling between the desired CPW mode and the unwanted coupled slotline mode is presented for finite ground
coplanar waveguides with unequal ground plane widths. Measurements, quasi-static conformal mapping, and Finite-
Difference Time-Domain analysis are performed to determine the dependence of the slotline mode excitation on the physical
dimensions of the FGC line and on the frequency range of operation. It is shown that the ratio of the slotline mode to the CPW
mode can be as high as 18 dB. The use of airbridges is shown to reduce the slotline mode by 15 dB, but that the slotline mode
fully reestablishes itself after 2000 microns. Furthermore, these results are independent of frequency.
Author
Waveguides; Coupled Modes; Planar Structures; Frequency Ranges
20040112058 NASA Glenn Research Center, Cleveland, OH, USA
High Mobility SiGe/Si n-MODFET Structures and Devices on Sapphire Substrates
Mueller, Carl; Alterovitz, Samuel; Croke, Edward; Ponchak, George; [2004]; 6 pp.; In English; Materials Research Society
Spring 2004 Conference, 10-14 Apr. 2004, San Francisco, CA, USA
Contract(s)/Grant(s): 22-090-20-C1; Copyright; Avail: CASI; A02, Hardcopy
Si/Ge/Si n-type modulation doped field effect structures and transistors (n-MODFET’s) have been fabricated on r-plane
sapphire substrates. Mobilities as high as 1380 cm(exp 2)/Vs were measured at room temperature. Excellent carrier
confinement was shown by Shubnikov-de Haas measurements. Atomic force microscopy indicated smooth surfaces, with rm’s
roughness less than 4 nm, similar to the quality of SiGe/Si n-MODFET structures made on Si substrates. Transistors with 2
micron gate lengths and 200 micron gate widths were fabricated and tested.
Derived from text
Doped Crystals; Modfets; Sapphire; Substrates; Sos (Semiconductors)
20040120860 NASA Glenn Research Center, Cleveland, OH, USA
LiCoO2 and SnO2 Thin Film Electrodes for Lithium-Ion Battery Applications
Maranchi, Jeffrey P.; Hepp, Aloysius F.; Kumta, Prashant N.; [2004]; 28 pp.; In English
Contract(s)/Grant(s): WBS 319-20-A1; Copyright; Avail: CASI; A03, Hardcopy
There is an increasing need for small dimension, ultra-lightweight, portable power supplies due to the miniaturization of
consumer electronic devices. Rechargeable thin film lithium-ion batteries have the potential to fulfill the growing demands for
micro-energy storage devices. However, rechargeable battery technology and fabrication processes have not kept paced with
the advances made in device technology. Economical fabrication methods lending excellent microstructural and compositional
control in the thin film battery electrodes have yet to be fully developed. In this study, spin coating has been used to
demonstrate the flexibility of the approach to produce both anode (SnO2) and cathode (LiCoO2) thin films. Results on the
microstructure crystal structure and electrochemical properties of the thin film electrodes are described and discussed.
Author
Electric Batteries; Thin Films; Microstructure
20040120879 NASA Langley Research Center, Hampton, VA, USA
A New Electromagnetic Instrument for Thickness Gauging of Conductive Materials
Fulton, J. P.; Wincheski, B.; Nath, S.; Reilly, J.; Namkung, M.; [1994]; 8 pp.; In English; Original contains color illustrations;
No Copyright; Avail: CASI; A02, Hardcopy
Eddy current techniques are widely used to measure the thickness of electrically conducting materials. The approach,
however, requires an extensive set of calibration standards and can be quite time consuming to set up and perform. Recently,
an electromagnetic sensor was developed which eliminates the need for impedance measurements. The ability to monitor the
magnitude of a voltage output independent of the phase enables the use of extremely simple instrumentation. Using this new
sensor a portable hand-held instrument was developed. The device makes single point measurements of the thickness of
nonferromagnetic conductive materials. The technique utilized by this instrument requires calibration with two samples of
known thicknesses that are representative of the upper and lower thickness values to be measured. The accuracy of the
instrument depends upon the calibration range, with a larger range giving a larger error. The measured thicknesses are typically
within 2-3% of the calibration range (the difference between the thin and thick sample) of their actual values. In this paper
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