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Master's Dissertation
Full name
Helder Nunes da Cunha
Knowledge Area
Date of Defense
São Carlos, 1989
Alfaro, Renê Armando Moreno
Faria, Roberto Mendonça
Motisuke, Paulo
Title in Portuguese
Efeito da radiação ultravioleta na despolarização termoestimulada de filmes de Teflon-Fep
Keywords in Portuguese
Não disponível
Abstract in Portuguese
Um estudo sistemático de despolarização termoestimulada (DTE) foi feito com filmes de Teflon-Fep irradiados com luz ultravioleta. As amostras foram irradiadas em três diferentes situações, na temperatura ambiente: a) Sem contatos metálicos, b) Com contatos metálicos, mas descarregadas e c) Com contatos metálicos, mas previamente carregadas. Foram utilizados contatos de In, Al, Zn, Cu, Cr e Au. As amostras carregadas negativamente despolarizaram-se quase na sua totalidade quando tinham sido irradiadas e estavam com contatos de In, Al e Zn, além de apresentarem sensíveis alterações nas curvas de DTE quando comparadas com as normais. As amostras com os outros contatos metálicos não foram muito alteradas pela radiação. Usando um modelo simplificado foi possível analisar as respostas do pulso térmico das amostras com carga residual e mostrou-se que houve injeção de buracos no caso das amostras irradiadas e carregadas negativamente. Medidas separadas usando amostras com dois contatos levaram à mesma conclusão. As amostras carregadas positivamente apresentaram uma carga residual considerável nas amostras irradiadas, evidenciando a presença de armadilhas profundas para buracos no volume do Teflon-Fep
Title in English
Not available
Keywords in English
Not available
Abstract in English
A systematic study of corona charged Teflon-Fep films previously irradiated with ultraviolet light by the thermal stimulated depolarization (TSD) was performed. The free surface was UV irradiated at room temperature under three different conditions: a) without a metallic contact on the other surface in a not yet charged sample. b) With a metallic contact in a not yet corona charged and c) With a metallic contact in a charged sample. Metallic contacts of In, Al, Zn, Cu, Cr and Au were used. The negatively charged samples become almost totally depolarized after the TSD when irradiated in both cases (b) and (c) of coated with In, Al and Zn contacts, showing also visible changes in the TSD curves as compared with the normal ones. Samples coating with Cu, Cr and Au contacts did not present major changes by the effect of UV radiation. Also, no effect was observed in case (a) whatsoever the nature of the electrode used. The analysis of the residual charge using the Heat Pulse Method (HPM) showed that positive charge was injected by the back electrode. Measurements with samples prepared as incase (b) above but now with a second contact seem also to indicate injection of positive charge. A simplified model is presented in order to explain the heat pulse response of negative irradiated samples. Positively corona charged samples under (a), (b) and (c) UV irradiation give different thermograms as compared as in unirradiated samples. The interpretation of the results is now more difficult but it seems that new deep hole traps are created by UV light
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