The structural and piezoresponse properties of c-axis-oriented Aurivillius phase Bi5Ti3FeO15 thin films deposited by atomic vapor deposition

Abstract

The deposition by atomic vapor deposition of highly c-axis-oriented Aurivillius phase Bi 5Ti 3FeO 15 (BTFO) thin films on (100) Si substrates is reported. Partially crystallized BTFO films with c-axis perpendicular to the substrate surface were first deposited at 610°C (8 excess Bi), and subsequently annealed at 820°C to get stoichiometric composition. After annealing, the films were highly c-axis-oriented, showing only (00l) peaks in x-ray diffraction (XRD), up to (0024). Transmission electron microscopy (TEM) confirms the BTFO film has a clear layered structure, and the bismuth oxide layer interleaves the four-block pseudoperovskite layer, indicating the n 4 Aurivillius phase structure. Piezoresponse force microscopy measurements indicate strong in-plane piezoelectric response, consistent with the c-axis layered structure, shown by XRD and TEM

Interesting Evidence for Template‐Induced Ferroelectric Behavior in Ultra‐Thin Titanium Dioxide Films Grown on (110) Neodymium Gallium Oxide Substrates

“…a-TiO2 thin films, with thickness ranging from 20-100nm, were deposited using a liquid injection chemical vapour deposition (atomic vapour deposition -AVD) [39] system on (110) NdGaO3(NGO) and (001) SrTiO3(STO) substrates. The temperature of the substrate was kept at 650°C during growth.…”

A study of the temperature dependence of the local ferroelectric properties of c-axis oriented Bi6Ti3Fe2O18 Aurivillius phase thin films: Illustrating the potential of a novel lead-free perovskite material for high density memory applications

“…It is well established that the magnitude of ferroelectric polarization (P s ) in layered Aurivillius phase structures is influenced by the number of perovskite units (n). 22 As noted earlier, Aurivillius phases with odd numbers of perovskite units have their spontaneous polarization vector along the in-plane a-axes and show weak or minor out-of-plane c-axis polarization (P s ), while Aurivillius phases with even numbers of perovskite units (n) show spontaneous response along in-plane a-axis polarization. 22,35 The amplitude response observed at room temperature demonstrates that the B6TFO films are piezoelectric, with comparably higher ferroelectric polarization strength and piezoresponses in the lateral a-axis direction ( figure 5(b)) with those measured in the vertical direction ( figure 4(a)).…”

“…The net volumetric precursor ratios transferred in vapour form into the reaction vapourizer (Trijet) are controlled by a computer controlled system operated at 220 • C. Due to the low deposition efficiency and volatile nature of bismuth at higher temperatures, 25% excess was added to compensate any bismuth deficiencies and to suppress the formation of mixed and pyrochlore phases during the annealing phase, as is well reported in literature for MOCVD (metal organic chemical vapour deposition) processes. 22,26 A liquid flow meter was used to monitor the net liquid flow during processing. The deposition temperature and pressure were kept at 610 • C and 10 mbar, respectively, while O 2 was used as a reactant gas with a flow rate of 600sccm (standard-state cubic centimetre per minute).…”

“…bismuth (thd) 3 ) in thin film form for high-k dielectrics and ferroelectric applications with high uniformity and control of thickness, orientation, texture and composition. 22 In this paper, we report the growth of c-axis oriented Bi 6 Ti 3 Fe 2 O 15 (n = 5) Aurivillius phase thin films on c-plane oriented sapphire substrates using the horizontal flow liquid injection chemical vapour deposition (LI-CVD) method. The potential of B6TFO for high temperature applications such as high temperature ferroelectric random access memories (Fe-RAMs) was explored at the nano-scale by analysing local piezoelectric and ferroelectric phenomena (domain switching, polarization writing and reading of patterns etc.)…”

“…[19][20][21] It is well-know that bismuth layer structured Arivilius phase thin films (BLSF) with oddnumbers of perovskite units show spontaneous polarization (P s ) along the in-plane a-axis and minor polarization along the out-of-plane c-axis, while even n-numbered films demonstrate response along the out-of-plane a-axis only. 22,35 Ferroelectric polarization in these materials is strongly hindered by additional impurity phases (such as pyrochlore). 23 These microstructural defects can be overcome by using optimised growth processes.…”