Growth of crystalline Al{sub 2}O{sub 3} via thermal atomic layer deposition: Nanomaterial phase stabilization

Katz, M. B.; Twigg, M. E.

doi:10.1063/1.4868300

Title: Growth of crystalline Al{sub 2}O{sub 3} via thermal atomic layer deposition: Nanomaterial phase stabilization

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Abstract

We report the growth of crystalline Al{sub 2}O{sub 3} thin films deposited by thermal Atomic Layer Deposition (ALD) at 200 °C, which up to now has always resulted in the amorphous phase. The 5 nm thick films were deposited on Ga{sub 2}O{sub 3}, ZnO, and Si nanowire substrates 100 nm or less in diameter. The crystalline nature of the Al{sub 2}O{sub 3} thin film coating was confirmed using Transmission Electron Microscopy (TEM), including high-resolution TEM lattice imaging, selected area diffraction, and energy filtered TEM. Al{sub 2}O{sub 3} coatings on nanowires with diameters of 10 nm or less formed a fully crystalline phase, while those with diameters in the 20–25 nm range resulted in a partially crystalline coating, and those with diameters in excess of 50 nm were fully amorphous. We suggest that the amorphous Al{sub 2}O{sub 3} phase becomes metastable with respect to a crystalline alumina polymorph, due to the nanometer size scale of the film/substrate combination. Since ALD Al{sub 2}O{sub 3} films are widely used as protective barriers, dielectric layers, as well as potential coatings in energy materials, these findings may have important implications.

Authors:

Katz, M. B.; Twigg, M. E. ^[1]

Naval Research Laboratory, Washington, District of Columbia 20375 (United States)

Publication Date:: Sat Mar 01 00:00:00 EST 2014

OSTI Identifier:: 22269549

Resource Type:: Journal Article

Journal Name:: APL Materials

Additional Journal Information:: Journal Volume: 2; Journal Issue: 3; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2166-532X

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; ALUMINIUM OXIDES; AMORPHOUS STATE; DEPOSITS; DIELECTRIC MATERIALS; DIFFRACTION; GALLIUM OXIDES; QUANTUM WIRES; STABILIZATION; SUBSTRATES; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY; ZINC OXIDES

Citation Formats


                    Prokes, S. M., E-mail: prokes@nrl.navy.mil, Katz, M. B., and Twigg, M. E. Growth of crystalline Al{sub 2}O{sub 3} via thermal atomic layer deposition: Nanomaterial phase stabilization.  United States: N. p., 2014. 
        Web.  doi:10.1063/1.4868300.

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                    Prokes, S. M., E-mail: prokes@nrl.navy.mil, Katz, M. B., & Twigg, M. E. Growth of crystalline Al{sub 2}O{sub 3} via thermal atomic layer deposition: Nanomaterial phase stabilization.  United States.  https://doi.org/10.1063/1.4868300

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                    Prokes, S. M., E-mail: prokes@nrl.navy.mil, Katz, M. B., and Twigg, M. E. 2014.  
        "Growth of crystalline Al{sub 2}O{sub 3} via thermal atomic layer deposition: Nanomaterial phase stabilization".  United States.  https://doi.org/10.1063/1.4868300.

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@article{osti_22269549,

  title        = {Growth of crystalline Al{sub 2}O{sub 3} via thermal atomic layer deposition: Nanomaterial phase stabilization},

  author       = {Prokes, S. M., E-mail: prokes@nrl.navy.mil and Katz, M. B. and Twigg, M. E.},

  abstractNote = {We report the growth of crystalline Al{sub 2}O{sub 3} thin films deposited by thermal Atomic Layer Deposition (ALD) at 200 °C, which up to now has always resulted in the amorphous phase. The 5 nm thick films were deposited on Ga{sub 2}O{sub 3}, ZnO, and Si nanowire substrates 100 nm or less in diameter. The crystalline nature of the Al{sub 2}O{sub 3} thin film coating was confirmed using Transmission Electron Microscopy (TEM), including high-resolution TEM lattice imaging, selected area diffraction, and energy filtered TEM. Al{sub 2}O{sub 3} coatings on nanowires with diameters of 10 nm or less formed a fully crystalline phase, while those with diameters in the 20–25 nm range resulted in a partially crystalline coating, and those with diameters in excess of 50 nm were fully amorphous. We suggest that the amorphous Al{sub 2}O{sub 3} phase becomes metastable with respect to a crystalline alumina polymorph, due to the nanometer size scale of the film/substrate combination. Since ALD Al{sub 2}O{sub 3} films are widely used as protective barriers, dielectric layers, as well as potential coatings in energy materials, these findings may have important implications.},

  doi          = {10.1063/1.4868300},

  url          = {https://www.osti.gov/biblio/22269549},
  journal      = {APL Materials},

  issn         = {2166-532X},

  number       = 3,

  volume       = 2,

  place        = {United States},

  year         = {Sat Mar 01 00:00:00 EST 2014},

  month        = {Sat Mar 01 00:00:00 EST 2014}

}

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