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Title: In situ study of the electronic structure of atomic layer deposited oxide ultrathin films upon oxygen adsorption using ambient pressure XPS

Abstract

In this work, ambient pressure X-ray photoelectron spectroscopy (APXPS) was used to investigate the effect of oxygen adsorption on the band bending and electron affinity of Al 2O 3, ZnO and TiO 2 ultrathin films (similar to 1 nm in thickness) deposited on a Si substrate by atomic layer deposition (ALD). Upon exposure to oxygen at room temperature (RT), upward band bending was observed on all three samples, and a decrease in electron affinity was observed on Al 2O 3 and ZnO ultrathin films at RT. At 80 °C, the magnitude of the upward band bending decreased, and the change in the electron affinity vanished. These results indicate the existence of two surface oxygen species: a negatively charged species that is strongly adsorbed and responsible for the observed upward band bending, and a weakly adsorbed species that is polarized, lowering the electron affinity. Based on the extent of upward band bending on the three samples, the surface coverage of the strongly adsorbed species exhibits the following order: Al 2O 3 > ZnO > TiO 2. Lastly, this finding is in stark contrast to the trend expected on the surface of these bulk oxides, and highlights the unique surface activity ofmore » ultrathin oxide films with important implications, for example, in oxidation reactions taking place on these films or in catalyst systems where such oxides are used as a support material.« less

Authors:
 [1];  [2];  [3];  [3];  [4];  [5];  [6];  [7]
  1. Soochow Univ., Suzhou (People's Republic of China); Chinese Academy of Sciences, Shanghai (People's Republic of China); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Argonne National Lab. (ANL), Argonne, IL (United States); Yale Univ., New Haven, CT (United States); The Univ. of Chicago, Chicago, IL (United States)
  5. Chinese Academy of Sciences, Shanghai (People's Republic of China); ShanghaiTech Univ., Shanghai (China)
  6. Soochow Univ., Suzhou (People's Republic of China)
  7. Chinese Academy of Sciences, Shanghai (People's Republic of China); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); ShanghaiTech Univ., Shanghai (China)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Materials Sciences and Engineering Division; National Natural Science Foundation of China (NNSFC)
OSTI Identifier:
1352564
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Catalysis Science and Technology
Additional Journal Information:
Journal Volume: 6; Journal Issue: 18; Journal ID: ISSN 2044-4753
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE

Citation Formats

Mao, Bao -Hua, Crumlin, Ethan, Tyo, Eric C., Pellin, Michael J., Vajda, Stefan, Li, Yimin, Wang, Sui -Dong, and Liu, Zhi. In situ study of the electronic structure of atomic layer deposited oxide ultrathin films upon oxygen adsorption using ambient pressure XPS. United States: N. p., 2016. Web. doi:10.1039/c6cy00575f.
Mao, Bao -Hua, Crumlin, Ethan, Tyo, Eric C., Pellin, Michael J., Vajda, Stefan, Li, Yimin, Wang, Sui -Dong, & Liu, Zhi. In situ study of the electronic structure of atomic layer deposited oxide ultrathin films upon oxygen adsorption using ambient pressure XPS. United States. doi:10.1039/c6cy00575f.
Mao, Bao -Hua, Crumlin, Ethan, Tyo, Eric C., Pellin, Michael J., Vajda, Stefan, Li, Yimin, Wang, Sui -Dong, and Liu, Zhi. 2016. "In situ study of the electronic structure of atomic layer deposited oxide ultrathin films upon oxygen adsorption using ambient pressure XPS". United States. doi:10.1039/c6cy00575f. https://www.osti.gov/servlets/purl/1352564.
@article{osti_1352564,
title = {In situ study of the electronic structure of atomic layer deposited oxide ultrathin films upon oxygen adsorption using ambient pressure XPS},
author = {Mao, Bao -Hua and Crumlin, Ethan and Tyo, Eric C. and Pellin, Michael J. and Vajda, Stefan and Li, Yimin and Wang, Sui -Dong and Liu, Zhi},
abstractNote = {In this work, ambient pressure X-ray photoelectron spectroscopy (APXPS) was used to investigate the effect of oxygen adsorption on the band bending and electron affinity of Al2O3, ZnO and TiO2 ultrathin films (similar to 1 nm in thickness) deposited on a Si substrate by atomic layer deposition (ALD). Upon exposure to oxygen at room temperature (RT), upward band bending was observed on all three samples, and a decrease in electron affinity was observed on Al2O3 and ZnO ultrathin films at RT. At 80 °C, the magnitude of the upward band bending decreased, and the change in the electron affinity vanished. These results indicate the existence of two surface oxygen species: a negatively charged species that is strongly adsorbed and responsible for the observed upward band bending, and a weakly adsorbed species that is polarized, lowering the electron affinity. Based on the extent of upward band bending on the three samples, the surface coverage of the strongly adsorbed species exhibits the following order: Al2O3 > ZnO > TiO2. Lastly, this finding is in stark contrast to the trend expected on the surface of these bulk oxides, and highlights the unique surface activity of ultrathin oxide films with important implications, for example, in oxidation reactions taking place on these films or in catalyst systems where such oxides are used as a support material.},
doi = {10.1039/c6cy00575f},
journal = {Catalysis Science and Technology},
number = 18,
volume = 6,
place = {United States},
year = 2016,
month = 7
}

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  • Ultrathin TaN and Ta 1-xAl xN y films with x = 0.21 to 0.88 were deposited by atomic layer deposition (ALD) and evaluated for Cu diffusion barrier effectiveness compared to physical vapor deposition (PVD) grown TaN. Cu diffusion barrier effectiveness was investigated using in-situ ramp anneal synchrotron X-ray diffraction (XRD) on Cu/1.8 nm barrier/Si stacks. A Kissinger-like analysis was used to assess the kinetics of Cu 3Si formation and determine the effective activation energy (E a) for Cu silicidation. Compared to the stack with a PVD TaN barrier, the stacks with the ALD films exhibited a higher crystallization temperature (Tmore » c) for Cu silicidation. The Ea values of Cu 3Si formation for stacks with the ALD films were close to the reported value for grain boundary diffusion of Cu whereas the Ea of Cu 3Si formation for the stack with PVD TaN is closer to the reported value for lattice diffusion. For 3 nm films, grazing incidence in-plane XRD showed evidence of nanocrystallites in an amorphous matrix with broad peaks corresponding to high density cubic phase for the ALD grown films and lower density hexagonal phase for the PVD grown film further elucidating the difference in initial failure mechanisms due to differences in barrier crystallinity and associated phase.« less
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