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Perfect Bi 4 Ti 3 O 12 Single‐Crystal Films via Flux‐Mediated Epitaxy
Author(s) -
Takahashi R.,
Yonezawa Y.,
Ohtani M.,
Kawasaki M.,
Nakajima K.,
Chikyow T.,
Koinuma H.,
Matsumoto Y.
Publication year - 2006
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200500390
Subject(s) - materials science , epitaxy , crystallinity , ferroelectricity , single crystal , stoichiometry , flux method , crystal (programming language) , crystal growth , nanotechnology , optoelectronics , crystallography , chemistry , computer science , composite material , layer (electronics) , dielectric , programming language
Excellent crystallinity of material films and atomic control of their surface/interface, sufficient for the realization of their optimal physical properties, are technological premises for modern functional‐device applications. Bi 4 Ti 3 O 12 and related compounds attract much interest as highly insulating, ferroelectric materials for use in ferroelectric random‐access memories. However, it has been difficult thus far for Bi 4 Ti 3 O 12 films to satisfy such requirements when formed using vapor‐phase epitaxy, owing to the high volatility of Bi in a vacuum. Here, we demonstrate that flux‐mediated epitaxy is one of the most promising and widely applicable concepts to overcome this inevitable problem. The key point of this process is the appropriate selection of a multi‐component flux system. A combinatorial approach has led to the successful discovery of the novel flux composition of Bi–Cu–O for Bi 4 Ti 3 O 12 single‐crystal film growth. The perfect single‐crystal nature of the stoichiometric Bi 4 Ti 3 O 12 film formed has been verified through its giant grain size and electric properties, equivalent to those of bulk single crystals. This demonstration has broad implications, opening up the possibility of preparing stoichiometric single‐crystal oxide films via vapor‐phase epitaxy, even if volatile constituents are required.