Avaliação do desempenho do óxido de alumínio com tratamento de superfície como dielétrico para capacitores MIS e OFETs
Carregando...
Arquivos
Data
2017-04-25
Autores
Silva, Marcelo Marques da [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Foi realizado um estudo sobre as propriedades elétricas de filmes finos de óxido de alumínio (Al2O3) obtidos por anodização em solução eletrolítica preparada com ácido tartárico, etileno glicol e água. Filmes de Al2O3 com espessuras entre 20 e 70 nm foram crescidos sobre camadas de alumínio as quais foram depositadas por evaporação em vácuo sobre lâminas de vidro. Utilizou-se o processo de anodização em duas etapas, sendo que na primeira etapa aplica-se uma corrente constante de 0,48 mA/cm2 e monitora a tensão até alcançar o valor final, programado conforme a espessura desejada; e então, na segunda etapa, mantem-se se a tensão final durante 2 minutos, enquanto mede-se a corrente. Os filmes de Al2O3 apresentam constante dielétrica média de aproximadamente sete (ε = 7), tan δ da ordem de 10-3 e resistividade elétrica da ordem de 1013 cm. Estudou-se o efeito do tratamento de superfície pela a deposição de monocamadas dos silanos, octadecil triclorosilano (OTS), hexametildisilazano (HMDS) e do ácido fosfônico (OPA) nas características elétricas. O tratamento com HMDS se mostrou o mais efetivo, diminuindo a corrente de fuga e aumentando campo de ruptura dielétrica. Também foi estudado o efeito do recobrimento, da superfície dos filmes de Al2O3, com filmes dos polímeros isolantes poliestireno (PS), polivinil álcool (PVA), fluoreto de polivinilideno (PVDF) e polimetilmetacrilato (PMMA). A deposição de um filme de PMMA foi a que apresentou os melhores resultados, com redução da corrente de fuga em torno de duas ordens de grandeza em relação aos filmes não tratados. Dispositivos com estrutura metal isolante e semicondutor (MIS) tendo o poli(3-hexyltiofeno) (P3HT) como semicondutor, também foram estudados com a finalidade de avaliar a aplicabilidade do Al2O3 como dielétrico em eletrônica orgânica. Conclui-se que filmes de Al2O3 preparados pela técnica de anodização com tratamento de superfície por deposição de uma monocamada de HMDS ou recoberto com um filme de PMMA é uma boa opção de dielétrico para eletrônica orgânica.
A study about electric properties of aluminum oxide (Al2O3) obtained by anodization of aluminum in a electrolytic solution prepared with tartaric acid, ethylene glycol and water was performed. Thin Al2O3 films from 20 to 70 nm were grown on aluminum layer which were deposited on glass slides by vacuum metallization. It was used the anodization process in two stages, being that in first stage applies a constant current of 0,48 mA/cm2 and monitory the voltage until reach the final value, programmed in according to the desired thickness; and in the second stage, the final voltage is maintained for two minutes, while the current is measured. The Al2O3 films present medium dielectric constant about seven (ε = 7), tan δ in order of 10-3 and resistivity in order of 1013 cm. It was studied the surface treatment effect by monolayers depositions of octadecyl trichlorosilane (OTS), hexamethyldisilazane (HMDS) and phosphonic acid (OPA) on the electrical characteristics. The HMDS treatment proved to be the most effective, reducing the leakage current and increasing the dielectric rupture field. The effect of the addition of polystyrene (PS), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF) and polymethylmethacrylate (PMMA) films on the oxide surface was also studied. The deposition of a PMMA film presented the best results, with reduction of the leakage current around two orders of magnitude in relation to pristine oxide. Devices with metal-insulator-semiconductor (MIS) structure, using the polymeric (3-hexythiophene) (P3HT) as semiconductors, also have been studied in order to evaluate the applicability of Al2O3 films as dielectric in organic electronics. It was concluded that Al2O3 films prepared by anodization, coated with a monolayer of HMDS or a thin PMMA film, are an excellent choice for apply as dielectric in organic electronics.
A study about electric properties of aluminum oxide (Al2O3) obtained by anodization of aluminum in a electrolytic solution prepared with tartaric acid, ethylene glycol and water was performed. Thin Al2O3 films from 20 to 70 nm were grown on aluminum layer which were deposited on glass slides by vacuum metallization. It was used the anodization process in two stages, being that in first stage applies a constant current of 0,48 mA/cm2 and monitory the voltage until reach the final value, programmed in according to the desired thickness; and in the second stage, the final voltage is maintained for two minutes, while the current is measured. The Al2O3 films present medium dielectric constant about seven (ε = 7), tan δ in order of 10-3 and resistivity in order of 1013 cm. It was studied the surface treatment effect by monolayers depositions of octadecyl trichlorosilane (OTS), hexamethyldisilazane (HMDS) and phosphonic acid (OPA) on the electrical characteristics. The HMDS treatment proved to be the most effective, reducing the leakage current and increasing the dielectric rupture field. The effect of the addition of polystyrene (PS), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF) and polymethylmethacrylate (PMMA) films on the oxide surface was also studied. The deposition of a PMMA film presented the best results, with reduction of the leakage current around two orders of magnitude in relation to pristine oxide. Devices with metal-insulator-semiconductor (MIS) structure, using the polymeric (3-hexythiophene) (P3HT) as semiconductors, also have been studied in order to evaluate the applicability of Al2O3 films as dielectric in organic electronics. It was concluded that Al2O3 films prepared by anodization, coated with a monolayer of HMDS or a thin PMMA film, are an excellent choice for apply as dielectric in organic electronics.
Descrição
Palavras-chave
Anodização, Óxido de alumínio, Al2O3, Tratamento de superfície, Capacitor MIS, Anodizing, Aluminum oxide, Surface treatment, MIS capacitor