Molecular beam epitaxy growth of BaTiO₃ thin films and crucial impact of oxygen content conditions on the electrical characteristics

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• 作者：G. Niu^a ; ^{gang.niu@ec-lyon.fr} ; B. Gautier^b ; S. Yin^a ; ^c ; G. Saint-Girons^a ; P. Lecoeur^d ; V. Pillard^d ; G. Hollinger^a ; B. Vilquin^a
• 关键词：Molecular beam epitaxy ; BaTiO3 ; Rectifying behavior ; Ferroelectric oxides ; Thin film
• 刊名：Thin Solid Films
• 出版年：2012
• 期刊代码：78_00406090
• 类别：ph
• 出版时间：1 May, 2012
• 卷：520
• 期：14
• 页码：4595-4599
• 文件大小：1100 K

摘要

In this study, high quality crystalline BaTiO₃ films were fabricated in different oxygen content conditions on Nb-doped SrTiO₃ (001) substrates by molecular beam epitaxy (MBE). BaTiO₃ epitaxial film presents a critical thickness of 6.4 nm and is almost entirely relaxed on SrTiO₃ with a thickness of ~ 50 nm. The electrical properties of 50 nm strain-free BaTiO₃ films were investigated by both macro- and microscopic measurements. Their electrical characteristics were found to be strongly influenced by different oxygen content conditions used during the preparation or annealing of the samples. Limited molecular oxygen partial pressure in a MBE chamber probably leads to a great amount of oxygen vacancies in the oxide film and results in rectification behavior of the oxygen-deficient BaTiO_3-x/SrTiO₃:Nb interface. Several approaches such as using atomic oxygen ambiance during the growth, annealing under elevated oxygen pressure were employed in order to decrease the oxygen vacancy density and these approaches eventually permit obtaining BaTiO₃ films with good ferroelectric characteristics.