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Desenvolvimento de filmes finos baseados em ZnO para aplicação em dispositivos memristivos
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Neste trabalho foram depositados filmes de óxido de zinco (ZnO) em substratos de vidro
com óxido de estanho e índio (substratos de ITO – Indium-doped Tin Oxide), através de pulverização catódica DC assistida por magnetrão, para aplicação em dispositivos com comportamento de memória resistiva (memrístores).
Os filmes de ZnO foram produzidos a partir de alvos metálicos de zinco numa descarga
reativa utilizando diferentes parâmetros de deposição, nomeadamente potência aplicada e a
pressão parcial de oxigénio, mantendo-se constantes a pressão de trabalho, o tempo de deposição e a distância entre os substratos e o alvo. Os filmes de ZnO foram sistematicamente
caracterizados por espetroscopia UV-Vis, espetroscopia Raman e do ponto de vista elétrico,
recorrendo a medidas de condutividade de superfície e de volume, assim como espectroscopia
de impedância.
A caracterização por espectroscopia UV-Vis mostrou que a transmitância aumenta com
o aumento da pressão parcial de oxigénio, o que demonstra a diminuição da espessura dos
filmes produzidos com este parâmetro. A formação de ZnO com estrutura wurtzite foi evidenciada por espectroscopia de Raman para todos os filmes depositados.
As medidas de condutividade de superfície, assim como as medidas de condutividade
de volume, através do método de quatro pontas revelaram que em todos os filmes testados,
foi possível identificar transições entre estados de baixa resistência e estados de elevada resistência, confirmando assim a boa aplicabilidade deste método e materiais para a produção de memrístores.
In this work, thin films of zinc oxide (ZnO) were deposited in conductive glass substrates (containing ITO – Indium-doped Tin Oxide), through DC magnetron sputtering, for application in devices with resistive memory behaviour (memristors). The ZnO films were produced from metallic zinc targets in a reactive discharge using different deposition parameters, namely applied power and partial pressure of oxygen, while keeping constant the working pressure, the deposition time and the distance between the substrates and the target. The ZnO films were systematically characterized by UV-Vis spectroscopy, Raman spectroscopy, and, from the electrical point of view, using surface and volume conductivity measurements, as well as impedance spectroscopy. The UV-Vis spectroscopy characterization showed that the transmittance increased with the increase of the partial pressure of oxygen, which demonstrated the decrease in the thickness of the films produced with the increase of this parameter. The formation of ZnO with wurtzite structure was evidenced by Raman spectroscopy for all deposited films The surface conductivity measurements, as well as the volume conductivity measurements, through the four probe method, revealed that in every film that was tested, it was possible to identify transitions between low-resistance states and high-resistance states, thus confirming the good applicability of this method for memristors production.
In this work, thin films of zinc oxide (ZnO) were deposited in conductive glass substrates (containing ITO – Indium-doped Tin Oxide), through DC magnetron sputtering, for application in devices with resistive memory behaviour (memristors). The ZnO films were produced from metallic zinc targets in a reactive discharge using different deposition parameters, namely applied power and partial pressure of oxygen, while keeping constant the working pressure, the deposition time and the distance between the substrates and the target. The ZnO films were systematically characterized by UV-Vis spectroscopy, Raman spectroscopy, and, from the electrical point of view, using surface and volume conductivity measurements, as well as impedance spectroscopy. The UV-Vis spectroscopy characterization showed that the transmittance increased with the increase of the partial pressure of oxygen, which demonstrated the decrease in the thickness of the films produced with the increase of this parameter. The formation of ZnO with wurtzite structure was evidenced by Raman spectroscopy for all deposited films The surface conductivity measurements, as well as the volume conductivity measurements, through the four probe method, revealed that in every film that was tested, it was possible to identify transitions between low-resistance states and high-resistance states, thus confirming the good applicability of this method for memristors production.
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óxido de zinco pulverização catódica DC assistida por magnetrão memrístores caracterização elétrica