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UV and ozone influence on the conductivity of ZnO thin films.

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Resumo:Complex impedance measurements were used to analyze the influence of ultraviolet and ozone gas on the electronic behaviour of ZnO films grown by rf magnetron sputtering. The data show that UV exposure strongly increases the ac conductivity of the film at very low frequencies, and that after ozone exposure it recovers the original value. At high frequencies, however, UV-light exposure it does not change the conductivity but the ozone acts in the sense to decrease it. Two distinct mechanisms, related to two relaxation time distributions are clearly observed: they are superimposed in the virgin sample, but they split forming two semicircles in the z00(f) z0 (f) diagrams when the samples are treated with UV and/or ozone gas. A combination of the bruggeman effective medium approximation (BEMA) with the random free energy barrier model is used to fit the data and to explain the ac conductivity variation phenomena observed.
Autores principais:Gonçalves, Gislayne Elisana
Outros Autores:Pimentel, A.; Fortunato, E.; Martins, R.; Queiroz, E. L.; Bianchi, Rodrigo Fernando; Faria, Roberto Mendonça
Assunto:Solar cells Semiconductors Sensors Conductivity
Ano:2015
País:Brasil
Tipo de documento:artigo
Tipo de acesso:unknown
Instituição associada:IBICT
Idioma:inglês
Origem:Oasisbr
Descrição
Resumo:Complex impedance measurements were used to analyze the influence of ultraviolet and ozone gas on the electronic behaviour of ZnO films grown by rf magnetron sputtering. The data show that UV exposure strongly increases the ac conductivity of the film at very low frequencies, and that after ozone exposure it recovers the original value. At high frequencies, however, UV-light exposure it does not change the conductivity but the ozone acts in the sense to decrease it. Two distinct mechanisms, related to two relaxation time distributions are clearly observed: they are superimposed in the virgin sample, but they split forming two semicircles in the z00(f) z0 (f) diagrams when the samples are treated with UV and/or ozone gas. A combination of the bruggeman effective medium approximation (BEMA) with the random free energy barrier model is used to fit the data and to explain the ac conductivity variation phenomena observed.

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