ISSN:
1573-8663
Keywords:
SBT
;
plasma
;
ferroelectric
;
SrBi2Ta2O9
;
pulsed laser ablation
;
film growth
;
oxygen plasma
;
film orientation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Growth of SrBi2Ta2O9 (SBT) thin films has been carried out in the presence of O2-plasma created by applying a potential at an auxiliary ring electrode placed near the substrate. Effect of plasma excitation potential and polarity, especially negative polarity, on the formation of a proper SBT phase at 700°C and in modifying crystallite orientation and microstructure of SBT films over (1 1 1) oriented Pt film coated over TiO2/SiO2/Si(1 0 0) substrates has been demonstrated. Preferred c-axis orientation of SBT films changes to (a–b) orientation with decrease in plasma excitation potential from −700 to −350 V and eliminates secondary Bi2Pt phase formation even at 600°C Microstructural study show a 2-dimensional large flat c-oriented crystallites formed at −700 V change to small crystallites in conformity with the changed aspect ratio for crystallites in (a–b) plane parallel to film plane. Spectroscopic ellipsometric results are in agreement with the microstructural data. These affects are attributed to O2-ion bombardment during film growth which reduces nucleation barrier for growth of crystallites in (a–b) plane. O2-plasma sustains the cationic species formed by laser ablation, which along with O 2 + ions, provide necessary activation energy and enhance the oxidation rates required for SBT phase formation even at 700°C. SBT films grown in O2-plasma show enhancement in remnant polarization value from 1.2 to 6.6 μC/cm2 and display ferroelectric properties superior to those formed without plasma. Further O2-plasma eliminates post deposition annealing step for observance of enhanced polarization values. This study shows O2-plasma excitation potential could be exploited as a new process parameter in laser ablation growth of ferroelectric oxide thin films.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1009929109536
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