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The Effect of Gallium Doping on Field Emission Property of ZnO Nanowires

Mokhtari, Arian | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58204 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Khademi, Ali; Moshfegh, Alireza
  7. Abstract:
  8. The persistent demand for advanced materials in the field of field emission has driven extensive research into semiconductor nanostructures. Among these, zinc oxide (ZnO) nanowires have emerged as promising candidates due to their high aspect ratio, favorable thermal stability, and outstanding electronic properties, including a wide energy bandgap. However, the intrinsic limitations of pure ZnO nanowires, such as low electron mobility and suboptimal work function, necessitate enhancements to meet the performance requirements of high-efficiency field emission devices. Doping the crystalline structure of ZnO with Group III elements from the periodic table transforms it into an n-type semiconductor. A two-step hydrothermal sol-gel synthesis process was employed to fabricate gallium-doped ZnO nanowires with distinct morphologies and ordered array structures, as confirmed by field emission scanning electron microscopy (FESEM). Additionally, the gallium doping levels in each sample were characterized and analyzed using energy-dispersive X-ray spectroscopy (EDS). In this study, the field emission properties of ZnO nanowires doped with various gallium concentrations were measured in a customized field emission setup. The turn-on fields for undoped, 1%, 2%, 3%, and 4% gallium-doped samples were measured as 6.94, 3.71, 1.50, 3.70, and 7.06 V/µm, respectively. The pre-threshold fields for these samples were determined to be 10.45, 8.21, 3.75, 6.95, and 9.94 V/µm. Furthermore, the field enhancement factor (β) was calculated to be 1502, 10256, 21795, 4001, and 1472 for the respective samples. The results indicate that doping ZnO nanowires up to 2% of gallium significantly improves their field emission properties. However, higher doping concentrations lead to a decline in performance due to the introduction of structural disorder within the nanowire arrays
  9. Keywords:
  10. Field Emission ; Hydrothermal Synthesis ; Zinc Oxide Nanowires ; Gallium Doping

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