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Title: High-surface-area ceria prepared by ALD on Al 2 O 3 support

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Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Applied Catalysis. B, Environmental
Additional Journal Information:
Journal Volume: 201; Journal Issue: C; Related Information: CHORUS Timestamp: 2018-04-21 18:25:33; Journal ID: ISSN 0926-3373
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Citation Formats

Onn, Tzia Ming, Zhang, Shuyi, Arroyo-Ramirez, Lisandra, Xia, Ye, Wang, Cong, Pan, Xiaoqing, Graham, George W., and Gorte, Raymond J.. High-surface-area ceria prepared by ALD on Al 2 O 3 support. Netherlands: N. p., 2017. Web. doi:10.1016/j.apcatb.2016.08.054.
Onn, Tzia Ming, Zhang, Shuyi, Arroyo-Ramirez, Lisandra, Xia, Ye, Wang, Cong, Pan, Xiaoqing, Graham, George W., & Gorte, Raymond J.. High-surface-area ceria prepared by ALD on Al 2 O 3 support. Netherlands. doi:10.1016/j.apcatb.2016.08.054.
Onn, Tzia Ming, Zhang, Shuyi, Arroyo-Ramirez, Lisandra, Xia, Ye, Wang, Cong, Pan, Xiaoqing, Graham, George W., and Gorte, Raymond J.. Wed . "High-surface-area ceria prepared by ALD on Al 2 O 3 support". Netherlands. doi:10.1016/j.apcatb.2016.08.054.
title = {High-surface-area ceria prepared by ALD on Al 2 O 3 support},
author = {Onn, Tzia Ming and Zhang, Shuyi and Arroyo-Ramirez, Lisandra and Xia, Ye and Wang, Cong and Pan, Xiaoqing and Graham, George W. and Gorte, Raymond J.},
abstractNote = {},
doi = {10.1016/j.apcatb.2016.08.054},
journal = {Applied Catalysis. B, Environmental},
number = C,
volume = 201,
place = {Netherlands},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.apcatb.2016.08.054

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  • Our study compares the physical, chemical and electrical properties of Al 2O 3 thin films deposited on gallium polar c- and nonpolar m -plane GaN substrates by atomic layer deposition (ALD). Correlations were sought between the film's structure, composition, and electrical properties. The thickness of the Al 2O 3 films was 19.2 nm as determined from a Si witness sample by spectroscopic ellipsometry. We measured the gate dielectric was slightly aluminum-rich (Al:O=1:1.3) from X-ray photoelectron spectroscopy (XPS) depth profile, and the oxide-semiconductor interface carbon concentration was lower on c -plane GaN. The oxide's surface morphology was similar on both substrates,more » but was smoothest on c -plane GaN as determined by atomic force microscopy (AFM). Circular capacitors (50-300 μm diameter) with Ni/Au (20/100 nm) metal contacts on top of the oxide were created by standard photolithography and e-beam evaporation methods to form metal-oxide-semiconductor capacitors (MOSCAPs). Moreover, the alumina deposited on c -plane GaN showed less hysteresis (0.15 V) than on m -plane GaN (0.24 V) in capacitance-voltage (CV) characteristics, consistent with its better quality of this dielectric as evidenced by negligible carbon contamination and smooth oxide surface. These results demonstrate the promising potential of ALD Al 2O 3 on c -plane GaN, but further optimization of ALD is required to realize the best properties of Al 2O 3 on m -plane GaN.« less
  • The effect of deposition temperature (T{sub dep}) and subsequent annealing time (t{sub anl}) of atomic layer deposited aluminum oxide (Al{sub 2}O3) films on silicon surface passivation (in terms of surface recombination velocity, SRV) is investigated. The pristine samples (as-deposited) show presence of positive fixed charges, Q{sub F}. The interface defect density (D{sub it}) decreases with increase in T{sub dep} which further decreases with t{sub anl} up to 100s. An effective surface passivation (SRV<8 cm/s) is realized for T{sub dep} ≥ 200 °C. The present investigation suggests that low thermal budget processing provides the same quality of passivation as realized bymore » high thermal budget process (t{sub anl} between 10 to 30 min)« less
  • Mixed metal oxides with spinel-type structure are often used as model systems for catalytic studies, and some of them find current industrial usage. Magnesium aluminate, MgAl[sub 2]O[sub 4], acts as an efficient transfer catalyst for reducing sulfur dioxide emissions, and it can also be used as a convenient support for metal carbonyls and other catalyst precursor materials. For these applications, high surface area and accessible porosity are desirable properties. The classical method to prepare MgAl[sub 2]O[sub 4] involves high-temperature solid state reaction between MgO and Al[sub 2]O[sub 3], but severe sintering leads to very low surface areas. Suitable precursors havemore » been sought to obtain a high surface area spinel. They include coprecipitated hydroxides or oxalates and [gamma]-alumina impregnated with a magnesium nitrate solution. Reported surface areas of MgAl[sub 2]O[sub 4] samples obtained from these precursors, after mild calcination at about 800 K, are in the 50-120 m[sup 2]g[sup [minus]1] range. The authors describe here the preparation and characterization of MgAl[sub 2]O[sub 4], and also Al[sub 2]O[sub 3]-MgAl[sub 2]O[sub 4] solid solutions, with surface areas of 250-300 m[sup 2]g[sup [minus]1]. Interest in the solid solutions stems from the fact that gradual changes of chemical composition provide a means to modulate surface acidity. 17 refs., 3 figs., 1 tab.« less
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