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Structural and Ferroelectric Properties of Epitaxial La0.5Sr0.5CoO3/Ba0.4Sr0.6TiO3/La0.5Sr0.5CoO3 Thin-Film Capacitors on Silicon for Dram Applications

Published online by Cambridge University Press:  15 February 2011

Pang-Jen kung
Affiliation:
Advanced Fuel Research, Inc., 87 Church Street, East Hartford, CT 06108
David B. Fenner
Affiliation:
Advanced Fuel Research, Inc., 87 Church Street, East Hartford, CT 06108
Qi Li
Affiliation:
Advanced Fuel Research, Inc., 87 Church Street, East Hartford, CT 06108
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Abstract

Epitaxial La0.5Sr0.5CoO3/Ba0.4Sr0.6Tio3/La0.5Sr0.5CoO3 heterostructures were grown (650- 750 °C) on yttria-stabilized zirconia (YSZ)-buffered silicon (100) by pulsed laser (Nd:YAG) deposition. A 15-nm-thick YBa2Cu3O7 film was deposited on the YSZ to act as a template layer for epitaxial growth of the subsequent conductive oxide and ferroelectric film layers. The Ba0.4Sr0.6TiO3 film was (h00) oriented normal to the Si-wafer surface. The temperaturedependent resistance curve measured on the La0.5Sr0.5CoO3 top electrode layer was found to indicate to some extent the film quality of the underlying layers. Hundreds of capacitors, fabricated by wet chemical etching from the as-deposited films, exhibited dc leakage current densities in the range of 0.05–0.1 μA/cm2 at 1-volt operation. By increasing the thickness of the dielectric layer, some of them were able to be tested at up to 20 volts before resistive leakage became dominant. To reduce leakage current densities and increase dielectric constants in these film capacitors for dynamic random access memory (DRAM) applications, we have made efforts to incorporate hybrid Pt/La0.5Sr0.5CoO3 bottom electrodes into capacitors. This results in improved dielectric constants (451 at 10 kHz) and P-E hysteresis characteristics (Ec = 58 kV/cm, Pr = 7.5 μC/cm2, and Pg = 25 μC/cm2).

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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References

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