Oxygen-Deficient Oxide Growth by Subliming the Oxide Source Material: The Cause of Silicide Formation in Rare Earth Oxides on Silicon

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• 作者：Oliver Bierwagen ; Andr茅 Proessdorf ; Michael Niehle ; Frank Grosse ; Achim Trampert ; Max Klingsporn
• 刊名：Crystal Growth & Design
• 出版年：2013
• 出版时间：August 7, 2013
• 年：2013
• 卷：13
• 期：8
• 页码：3645-3650
• 全文大小：432K
• 年卷期：v.13,no.8(August 7, 2013)
• ISSN：1528-7505

文摘

The fundamental issue of oxygen stoichiometry in oxide thin film growth by subliming the source oxide is investigated by varying the additionally supplied oxygen during molecular beam epitaxy of RE₂O₃ (RE = Gd, La, Lu) thin films on Si(111). Supplying additional oxygen throughout the entire growth was found to prevent the formation of rare earth silicides observed in films grown without an oxygen source. Postgrowth vacuum annealing of oxygen stoichiometric films did not lead to silicide formation thereby confirming that the silicides do not form as a result of an interface instability at growth temperature in vacuum but rather due to an oxygen deficiency in the source vapor. The average oxygen deficiency of the rare-earth containing species in the source vapor was quantified by the ¹⁸O tracer technique and correlated with that of the source material, which gradually decomposed during sublimation. Therefore, any oxide growth by sublimation of the oxide source material requires additional oxygen to realize oxygen stoichiometric films.