were done to determine the practicality of using cfradar dielectric waveguide for a low-has tramumw " ion line at miffimeter wavelength The lowest order mode on a circufar dielectric guide will PWWa@ r%m'df= of how SUUJJ the guide diameter is. TIM attenuation factor of this mode is proportional to the diameter. llms it is possible to make tie attenuation factor of a circufar dielectric guide arbitrarily srmdf by reducing its diameter. Loss measurements for several different diameters of polystyrene and Teflon rods were made at 72.70 GHz. The measurements were made by directly prob~long sections of dielectric guide and plotting the average power as a function of length on an X-Y plotter. Dielectric constants were measured from the standing wave patterns of polystyrene Teflon, and fused quartz rods at 71.0 GHz, Teflon rodv exhibited attenuation factors from 0.8 (fB/m to 2.2 dB/w dependfng on the diameter. 'Ihfs is an improvement over sifver wavegufde at this frequency. Polystyrene rods were fmmd to have attenuation factors t@g from 3.9 dB/m to 12.5 dB/mj again depending on the diameter of the rod. 'f'he measured dielectric constants are consistent with prevfoualy publisbed data. 'Ihe various attenuation factors are related to the fntridc loss tangent of the dielectric using the theory of the HEll mode. Vafuea of tan C3 derived from measurements of different rods are conaisten~indicating that the experimental results are valid The problem of radiation from dielectric rods is discussed. The experimental reaufta are not eonclusivej but it appears fikely that radiation loss is negligible.
We have investigated the growth of silicon polycrystals from deposited amorphous films on several different substrates. Using Raman spectroscopy, x-ray diffraction, transmission electron microscopy, and optical microscopy, we find that substrate choice affects crystallite size, preferential orientation, and growth rate. In addition, it is shown that large high quality crystals can be grown on low cost glasses.
We report on the first polycrystalline-silicon (poly-Si) thinfilm transistor (TFT) deposited at low temperature on Corning 7059 glass. It has immediate practical applications for low-cost thin-film display and imaging electronics manufacturing. All the process steps used to fabricate the poly-Si device occurred at temperatures of 550°C or less. The poly-Si films exhibit crystallite grain sizes on the order of 5000 A, and the fabricated devices have shown field-effect mobilities of 10-20 cm2/V-s and threshold voltages around zero. We have also developed a novel plasma process to form the source and drain contacts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.