title: Ultrathin and Atomically Flat Transition-Metal Oxide: Promising Building Blocks for Metal-Insulator Electronics.
abstract: We present a new and viable template-assisted thermal synthesis method for preparing amorphous ultrathin transition-metal oxides (TMOs) such as TiO2and Ta2O5, which are converted from crystalline two-dimensional (2D) transition-metal dichalcogenides (TMDs) down to a few atomic layers. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM) were used to characterize the chemical composition and bonding, surface morphology, and atomic structure of these ultrathin amorphous materials to validate the effectiveness of our synthesis approach. Furthermore, we have fabricated metal-insulator-metal (MIM) diodes using the TiO2and Ta2O5as ultrathin insulating layers with low potential barrier heights. Our MIM diodes show a clear transition from direct tunneling to Fowler-Nordheim tunneling, which was not observed in previously reported MIM diodes with TiO2or Ta2O5as the insulating layer. We attribute the improved performance of our MIM diodes to the excellent flatness and low pinhole/defect densities in our TMO insulting layers converted from 2D TMDs, which enable the low-threshold and controllable electron tunneling transport. We envision that it is possible to use the ultrathin TMOs converted from 2D TMDs as the insulating layer of a wide variety of metal-insulator and field-effect electronic devices for various applications ranging from microwave mixing, parametric conversion, infrared photodetection, emissive energy harvesting, to ultrafast electronic switching.
authors.affiliation: Department of Electrical and Computer Engineering, ‡Department of Physics and Astronomy, and §Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Cui
authors.affiliation: Department of Electrical and Computer Engineering, ‡Department of Physics and Astronomy, and §Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Maryam
authors.initials: M
authors.lastname: Sakhdari
authors.affiliation: Department of Electrical and Computer Engineering, ‡Department of Physics and Astronomy, and §Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Bhim
authors.identifier: http://orcid.org/0000-0002-3412-8323
authors.initials: B
authors.lastname: Chamlagain
authors.affiliation: Department of Electrical and Computer Engineering, ‡Department of Physics and Astronomy, and §Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Hsun-Jen
authors.initials: HJ
authors.lastname: Chuang
authors.affiliation: Department of Electrical and Computer Engineering, ‡Department of Physics and Astronomy, and §Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Yi
authors.identifier: http://orcid.org/0000-0001-6996-8843
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Electrical and Computer Engineering, ‡Department of Physics and Astronomy, and §Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Mark Ming-Cheng
authors.initials: MM
authors.lastname: Cheng
authors.affiliation: Department of Electrical and Computer Engineering, ‡Department of Physics and Astronomy, and §Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Zhixian
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Electrical and Computer Engineering, ‡Department of Physics and Astronomy, and §Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States.
authors.forename: Pai-Yen
authors.initials: PY
authors.lastname: Chen
keywords: 2D materials; insulating nanomaterials; metal−insulator electronics; metal−insulator−metal diodes; transition-metal oxides; tunneling devices