Master of Science
Materials Science and Engineering
A new and viable template-assisted thermal synthesis method for preparation of amorphous ultrathin transition-metal oxides (TMOs) is proposed. A few atomic layers TiO2 and Ta2O5 are converted from crystalline two-dimensional (2D) transition-metal dichalcogenides (TMDs). Chemical composition and bonding, surface morphology, and atomic structure of these ultrathin amorphous materials were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM). In addition, we use TiO2 and Ta2O5 as ultrathin insulating layers with low potential barrier heights to fabricate metal-insulator-metal (MIM) diodes. A clear transition from direct tunneling to Fowler-Nordheim tunneling is shown in our MIM diodes, which was not observed in previously reported MIM diodes with TiO2 or Ta2O5 as insulating layer. We attribute the improved performance of the MIM diodes to the excellent flatness and low pinhole/defect densities of our TMO layers, which enable low-threshold and controllable electron tunneling transport. We imagine that the ultrathin TMOs converted from 2D TMDs can be used in various applications, including microwave mixing, parametric conversion, infrared photodetection, emissive energy harvesting, and ultrafast electronic switching.
Cui, Qingsong, "Template Assisted Transition-Metal Oxide As Ultrathin Insulator For Metal-Insulator Electronics" (2018). Theses and Dissertations. 4273.
Available for download on Friday, August 14, 2020