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Microstructure and Nonstoichiometry of Barium Strontium Titanate thin films for dram Applications

Published online by Cambridge University Press:  10 February 2011

S. Stemmer ,
S. K. Streiffer ,
N. D. Browning  and
A. I. Kingon
S. Stemmer
Affiliation:
Department of Physics, University of Illinois at Chicago, Chicago, IL 60607–7059, [email protected]
S. K. Streiffer
Affiliation:
Argonne National Laboratory, Materials Science Division, Argonne, IL 60439–4838
N. D. Browning
Affiliation:
Department of Physics, University of Illinois at Chicago, Chicago, IL 60607–7059, [email protected]
A. I. Kingon
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695–7907
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Abstract

In this paper we investigate the microstructural accommodation of nonstoichiometry in (BaxSr1-x)Ti1+yO3+Z thin films grown by chemical vapor deposition. Films with three different (Ba+Sr)/Ti ratios of 49/51 (y=0.04 in the notation of the formula above), of 48/52 (y = 0.08) and of 46.5/53.5 (y=0.15), were studied. High-resolution electron microscopy is used to study the microstructure of the BST films. High-spatial resolution electron energy-loss spectroscopy (EELS) is used to reveal changes in chemistry and local atomic environment both at grain boundaries and within grains as a function of titanium excess. We find an amorphous phase at the grain boundaries and grain boundary segregation of excess titanium in the samples with y=0.15. In addition, EELS is also used to show that excess titanium is being partially accommodated in the grain interior. Implications for the film electrical and dielectric properties are outlined.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 574: Symposia BB – Multicomponent Oxide Films for Electronics , 1999 , 119
Copyright
Copyright © Materials Research Society 1999

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