TY - JOUR
T1 - Nonuniform Composition Profiles in Amorphous Multimetal Oxide Thin Films Deposited from Aqueous Solution
AU - Woods, Keenan N.
AU - Thomas, Milana C.
AU - Mitchson, Gavin
AU - Ditto, Jeffrey
AU - Xu, Can
AU - Kayal, Donna
AU - Frisella, Kathleen C.
AU - Gustafsson, Torgny
AU - Garfunkel, Eric
AU - Chabal, Yves J.
AU - Johnson, David C.
AU - Page, Catherine J.
N1 - Funding Information:
This work was supported by the Center for Sustainable Materials Chemistry, which is funded by the NSF (CCI Grant CHE-1606982). C.X., T.G., and E.G. acknowledge additional support from the NSF (DMR 1106070). We gratefully acknowledge the use of UO CAMCOR High-Resolution and Nanofabrication Facility that are supported by grants from the W. M. Keck Foundation, the M. J. Murdock Charitable Trust, ONAMI, the Air Force Research Laboratory (Agreement No. FA8650-05-1-5041), NSF (Award Nos. 0923577 and 0421086), and the University of Oregon. We also acknowledge support through the Collaborative Access Team (CAT): Pooled Resources for Electron Microscopy Informatics, Education and Research (PREMIER) Network Program at Pacific Northwest National Laboratory (PNNL) and the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research at PNNL. PNNL is a multiprogram national laboratory operated by Battelle for DOE under contract DE-AC05-76RL01830. The authors thank Devin R. Merrill and Suzannah R. Wood for XRR instrument expertise, Erik Hadland and Sage R. Bauers for assistance with XRR modeling, and Paul N. Plassmeyer, Charith E. Nanayakkara, and Aaron M. Dangerfield for valuable scientific discussions.
PY - 2017/10/25
Y1 - 2017/10/25
N2 - Metal oxide thin films are ubiquitous in technological applications. Often, multiple metal components are used to achieve desired film properties for specific functions. Solution deposition offers an attractive route for producing these multimetal oxides because it allows for careful control of film composition through the manipulation of precursor stoichiometry. Although it has been generally assumed that homogeneous precursor solutions yield homogeneous thin films, we recently reported evidence of nonuniform electron density profiles in aqueous-deposited films. Herein, we show that nonuniform electron densities in lanthanum zirconium oxide (LZO) thin films are the result of inhomogeneous distributions of metal components. Specifically, La aggregates at the film surface, whereas Zr is relatively evenly distributed throughout single-layer films. This inhomogeneous metal distribution persists in stacked multilayer films, resulting in La-rich interfaces between the sequentially deposited layers. Testing of metal-insulator-semiconductor devices fabricated from single and multilayer LZO films shows that multilayer films have higher dielectric constants, indicating that La-rich interfaces in multilayer films do not detrimentally impact film properties. We attribute the enhanced dielectric properties of multilayer films to greater condensation and densification relative to single-layer films, and these results suggest that multilayer films may be preferred for device applications despite the presence of layering artifacts.
AB - Metal oxide thin films are ubiquitous in technological applications. Often, multiple metal components are used to achieve desired film properties for specific functions. Solution deposition offers an attractive route for producing these multimetal oxides because it allows for careful control of film composition through the manipulation of precursor stoichiometry. Although it has been generally assumed that homogeneous precursor solutions yield homogeneous thin films, we recently reported evidence of nonuniform electron density profiles in aqueous-deposited films. Herein, we show that nonuniform electron densities in lanthanum zirconium oxide (LZO) thin films are the result of inhomogeneous distributions of metal components. Specifically, La aggregates at the film surface, whereas Zr is relatively evenly distributed throughout single-layer films. This inhomogeneous metal distribution persists in stacked multilayer films, resulting in La-rich interfaces between the sequentially deposited layers. Testing of metal-insulator-semiconductor devices fabricated from single and multilayer LZO films shows that multilayer films have higher dielectric constants, indicating that La-rich interfaces in multilayer films do not detrimentally impact film properties. We attribute the enhanced dielectric properties of multilayer films to greater condensation and densification relative to single-layer films, and these results suggest that multilayer films may be preferred for device applications despite the presence of layering artifacts.
KW - density gradients
KW - lanthanum zirconium oxide
KW - layering artifacts
KW - multilayer thin films
KW - nonuniform composition
KW - solution deposition
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U2 - 10.1021/acsami.7b12462
DO - 10.1021/acsami.7b12462
M3 - Article
C2 - 28959877
AN - SCOPUS:85032896193
VL - 9
SP - 37476
EP - 37483
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
SN - 1944-8244
IS - 42
ER -