Design and preparation of stress-free epitaxial BaTiO₃polydomain films by RF magnetron sputtering

Abstract

Domain structures of BaTiO 3 thick films grown on (100) SrTiO 3 single-crystal substrates were engineered using an RF magnetron sputtering deposition process. By tuning the sputtering power and cooling rate and using an off-axis sputtering technique to prepare conducting perovskite oxide bottom electrode with heteroepitaxial quality, we have deposited epitaxial tetragonal single-domain and polydomain BaTiO 3 films with a self-assembled three-domain architecture. The electrical properties and microstructure of the BaTiO 3 films were characterized, and a c/a 1 /a 2 cellular polydomain structure was clearly observed in as-grown films by optical microscopy. Such a polydomain structure was a consequence of a complete relaxation of misfit stresses of the film. Engineering of this self-assembled microstructure has great potential in providing large, field-tunable pyroelectric and electromechanical responses in next-generation microelectronic devices and micro-electro-mechanical systems (MEMS).

Effect of elastic domains on electromechanical response of epitaxial ferroelectric films with a three-domain architecture

“…Transmission electron microscopy (TEM) [25] and piezoelectric force microscopy (PFM) [13,23] studies of tetragonal PZT 20/80 films thicker than 300 nm show that they have a cellular architecture that completely relaxes the internal stresses. An optical microscopy study of epitaxial tetragonal BaTiO 3 thick films also illustrates similar morphology of a three-domain structure [14]. These polydomain films are divided into cells of c-domains along the (001) direction bound by a 1 -and a 2 -domains of equal domain fraction along the (100) and (010) directions, respectively ( Fig.…”

“…The three-domain structures have been observed in ferroelectric tetragonal PbZrTiO 3 [26] and BaTiO 3 [14] films with thickness of more than 300 nm, and it has been shown that the misfit stress in these films is close to zero. Since the equilibrium three-domain films are stress-free in the absence of an external electric field and the field-induced deviation of structure and polarization from the equilibrium are small, the linear theory is adequate for analyzing their electromechanical properties.…”

“…Particularly, the switching of elastic domains increases the compliance of polydomain phases to external mechanical, electrical or magnetic fields. The concept of elastic domains has been successfully applied to the analysis of polydomain microstructures in epitaxial films [4], and numerous polydomain structures in epitaxial films of superconductors [5], semiconductors [6], ferromagnetic [7] and ferroelectrics [8][9][10][11][12][13][14][15] have been studied experimentally and theoretically.…”

Preparation and characterization of self-assembled percolative BaTiO3–CoFe2O4 nanocomposites via magnetron co-sputtering

“…On the other hand, film B only shows {001} and {400} preferred orientations in BTO and CFO phases, respectively, most likely due to an enhanced strain effect in the composite film. Compared with those of the pure films, the diffraction peaks of BTO and CFO component phases in the composite films were shifted to lower 2 θ angles, indicating the existence of uncompensated misfit stresses in the composite films [26]. …”

Particle processing technology

“…(5) The modeling and development of the ECAS process [6]. This involves two-step pressure application [23] and high-pressure application above 400 MPa to fabricate transparent oxides [24][25][26], and rapid heating to obtain dense nanocomposites of ceramic-CNT [27] and diamonds [28]. (6) The contraction of ternary phase diagrams for oxide ion conductor systems such as zirconia [29] and apatite systems [30], leading to an increased understanding of the stability of such systems and assisting the search for high oxygen ion conductors.…”