Chemical and electrochemical synthesis techniques have been the principal methods of obtaining polymers in industry and scientific research laboratories. However, during the last two decades, ...photochemical synthesis, although poorly studied, has been reported to present several advantages, in that it is a fast and cheap technique, and it is not aggressive to the environment. The technique has been applied to the production of some conducting polymers. In this study, semiconducting polymeric blends composed of PT3AA-KPVDF and PT3MAPVDF were respectively obtained by photochemical polymerization in aqueous solutions of 3-thiophene acetic acid and 3-thiophene methyl acetate monomers using PVDF microporous matrices and potassium dichromate as catalyst. The percentage of products and by-products incorporated in the host matrix was obtained by gravimetric analysis. The chemical structures of the polymers synthesized were analyzed by FTIR, UV-vis and
1
H NMR. GPC analysis indicated the formation of oligomers composed of 56 mers. The morphology of the matrices and polymeric blends was observed by SEM-EDS and their electric behavior evaluated by measures of electric conductivity. The SEM images show the presence of polythiophene in the pores of the PVDF microporous membrane. The thermal properties of the polymers and their blends were evaluated by DSC and TGA. Thermal analysis by DSC demonstrated an increase in melting temperature of the blends, attributed to the confinement of PVDF crystalline phases for the polymer photosynthesized. The results of volumetric conductivity measurements of polymeric blends show an increase in conductivity in the matrices from 10
15
to 10
11
S cm
1
.
Chemical and electrochemical synthesis techniques have been the principal methods of obtaining polymers in industry and scientific research laboratories.
Solar observations at sub-THz frequencies detected a new flare spectral component peaking in the THz range, simultaneously with the well known microwaves component, bringing challenging constraints ...for interpretation. Higher THz frequencies observations are needed to understand the nature of the mechanisms occurring in flares. A THz photometer system was developed to observe outside the terrestrial atmosphere on stratospheric balloons or satellites, or at exceptionally transparent ground stations. The telescope was designed to observe the whole solar disk detecting small relative changes in input temperature caused by flares at localized positions. A Golay cell detector is preceded by low-pass filters to suppress visible and near IR radiation, a band-pass filter, and a chopper. A prototype was assembled to demonstrate the new concept and the system performance. It can detect temperature variations smaller than 1 K for data sampled at a rate of 10/s, smoothed for intervals larger than 4 s. For a 76 mm aperture, this corresponds to small solar burst intensities at THz frequencies. A system with 3 and 7 THz photometers is being built for solar flare observations on board of stratospheric balloon missions.
CV characteristics of polycrystalline sige films with low GE concentration Teixeira, Ricardo Cotrin; Doi, Ioshiaki; Diniz, José Alexandre ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
December 2006, 2006-12-00, Letnik:
253, Številka:
1-2
Journal Article
Recenzirano
SiGe alloys are currently used for HBT and MOS as epitaxial layers for base or strained channel, respectively. In the poly phase, SiGe has been studied as a replacement for poly-Si in MOS gates due ...to its lower thermal budget and gate depletion and also due to the Workfunction Engineering for Vt adjustments. However, for application to CMOS technology as poly-SiGe gates, others constrains emerge such as quality of the oxide interface and etch chemistry. For both applications, the Ge fraction normally lies between 20% and 40%. In this study, authors use a low Ge contents (1%) poly-SiGe thin films aiming for MOS gate electrode. The Ge fraction was determined by RBS analysis. 230nm thick samples were deposited onto 10nm thermally oxidized 〈100〉, p-type Si substrates using silane and germane. Films were deposited in the temperature of 500°C and total pressure of 667Pa (5Torr) by vertical LPCVD. The samples were doped using 31P+ ion implantation from 5×1014cm−2 up to 2×1016cm−2 and annealed by RTP (40s) from 500°C up to 900°C. Rs values were obtained by 4-point probe technique and CV curves were extracted from nMOS capacitors with 200μm diameter. The same processing steps were used to fabricate similar poly-Si samples and capacitors for comparison.
The poly-SiGe samples presented Rs values one order of magnitude lower than poly-Si and CV analysis of nMOS capacitors showed very good characteristics. The 1% Ge in the alloy ensures a low thermal budget for the overall process. Although a relatively high annealing temperature (800°C) must be used to reduce oxide charge and interface traps, the temperature is well below the necessary for poly-Si processing and can allow formation of the shallow junctions needed for next technological nodes.
Orientador: Navin B. Patel
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Previous issue date: 1989
Resumo: Não informado
Abstract: Not informed.
Doutorado
Física
Doutor em Ciências
Orientador: Navin B. Patel
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Previous issue date: 1975
Resumo: Não informado
Abstract: Not informed.
Mestrado
Física
Mestre em Física
Solar observations at sub-THz frequencies detected a new flare spectral component peaking in the THz range, simultaneously with the well known microwaves component, bringing challenging constraints ...for interpretation. Higher THz frequencies observations are needed to understand the nature of the mechanisms occurring in flares. A THz photometer system was developed to observe outside the terrestrial atmosphere on stratospheric balloons or satellites, or at exceptionally transparent ground stations. The telescope was designed to observe the whole solar disk detecting small relative changes in input temperature caused by flares at localized positions. A Golay cell detector is preceded by low-pass filters to suppress visible and near IR radiation, a band-pass filter, and a chopper. A prototype was assembled to demonstrate the new concept and the system performance. It can detect temperature variations smaller than 1 K for data sampled at a rate of 10/second, smoothed for intervals larger than 4 seconds. For a 76 mm aperture, this corresponds to small solar burst intensities at THz frequencies. A system with 3 and 7 THz photometers is being built for solar flare observations on board of stratospheric balloon missions.
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