Flexible nano-memory device by zinc oxide nanorod arrays

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University of Alabama Libraries

Memory is one of the key techniques for information technology. It is highly desired to have memory device with flexible characteristic for special applications. The challenges for archiving flexible memory are not only restrained by current materials but also existing memory mechanism, while nanomaterials exhibit size dependent properties that are different from their bulk form, discovering in new materials and architectures design as well as novel working principle provides an alternative approach to meet the objectives. In this dissertation, a comprehensive study on developing flexible nano-memory device from fundamental semiconducting nanomaterial to device’s architecture design and performance is presented. With the strong basis support, the as-fabricated flexible nano-memory device exhibits extraordinary memory characteristics and excellent flexibility. First, controllable synthesis of zinc oxide (ZnO) nanorod/nanowire (NR/NW) is the prerequisite to provide desired nanomaterials and nanostructures, the effect from substrate roughness is the key to grow well-aligned three-dimensional (3D) ZnO nanostructures for fabricating patterned nano-memory. Second, because the performance of device is closely related to the material’s property, electrical property of one-dimensional (1D) ZnO nanomaterial by experimental and theoretical approaches have been characterized. The results reveal that the electrical resistance has nonlinear length dependence in the single crystal ZnO microbelt/nanobelt (MB/NB), which is significantly different with the bulk counterpart. Finite element simulation can identify the crystallography of the anisotropic semiconducting nanomaterial. Third, when nanomaterials with a height-diameter ratio in-between zero-dimensional (0D) and 1D, its photoelectric properties will not follow the traditional Ohm’s law because of the additional nanoconfinement from the third dimension. Photoelectric property change in half-dimensional (0.5D) ZnO nanomaterials as a function of illumination light intensity and materials geometry has been systematically studied. A new proposed model could more accurately predict the photoelectric characteristics of 0.5D semiconducting nanomaterials. Last, based on fundamental synthesis and properties characterization above, a new flexible nano-memory device based on ZnO NW arrays is fabricated. Benefited from 3D nanostructures and the unique polar charges screening effect induced electric hysteresis loop memory mechanism, the nano-memory device has outstanding performances in unit down to nanoscale, operation speed up to gigahertz, as well as excellent flexibility.

Electronic Thesis or Dissertation
Materials science, Nanoscience, Nanotechnology