Here is a new interesting paper on ferroelectric BFO deposited in an Ultratech Cambridge Nanotech Savannah reactor Institut
de Ciencia de Materials de Barcelona (ICMAB-CSIC). The thermal ALD process at 250 °C by alternate pulsing of bismuth
tris(2,2,6,6-tetramethyl-3,5-heptanedionate) (Bi(thd)3) and ferrocene (Fe(Cp)2) combined with ozone (O3)
Nanocrystalline Ferroelectric BiFeO3 Thin Films by Low-Temperature ALD
Mariona Coll*, Jaume Gazquez, Ignasi Fina, Zakariya Khayat,
Andy Quindeau, Marin Alexe, Maria Varela, Susan Trolier-McKinstry, Xavier
Obradors, and Teresa Puig;
Chem. Mater., 2015, 27 (18), pp 6322–6328
In this
work, ferroelectricity is identified in nanocrystalline BiFeO3 (BFO) thin films
prepared by low-temperature atomic layer deposition. A combination of X-ray
diffraction, reflection high energy electron diffraction, and scanning
transmission electron microscopy analysis indicates that the as-deposited films
(250 °C) consist of BFO nanocrystals embedded in an amorphous matrix.
Postannealing at 650 °C for 60 min converts the sample to a crystalline film on
a SrTiO3substrate. Piezoelectric force microscopy demonstrates the existence of
ferroelectricity in both as-deposited and postannealed films. The ferroelectric
behavior in the as-deposited stage is attributed to the presence of
nanocrystals. Finally, a band gap of 2.7 eV was measured by spectroscopic
ellipsometry. This study opens broad possibilities toward ferroelectric oxides
on 3D substrates and also for the development of new ferroelectric perovskites
prepared at low temperature.
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