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Electrical and Optical Characterization of Fabricated Carbon-Based Multilayer Structure versus Temperature

Hooshyar, Parsa | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56931 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Fardmanesh, Mehdi; Zamani, Atieh
  7. Abstract:
  8. This study presents a comprehensive investigation into the characterization of three distinct homogeneous multilayer self-standing thin films, composed of stacked reduced graphene oxide (rGO) planes, which were synthesized using a modified Hummer’s method. In order to investigate their structural, electrical, and optical properties, the samples were characterized by field emission scanning electron microscopy (FESEM), Raman spectroscopy, four-point probe measurements, Impedance measurements, Fourier-transform infrared spectroscopy (FTIR), and Time domain Terahertz Spectroscopy (TDS). The FESEM images obtained from the samples reveal a smooth sheet-like surface with few wrinkles. Additionally, the cross-sectional images provide confirmation of the presence of multi-stacked layer structures. The Raman spectra of the samples indicate the presence of minor surface defects and a relatively low oxygen content of our rGO samples. Based on the resistance decrease by increasing the temperature, the electrical resistance vs. temperature curves imply semiconducting behavior in our rGO samples in three distinct electrical conductivity range. The impedance characterization based on AC measurements showcase that the samples are laterally pure resistive; also they exhibit a capacitive behavior in the out-of-plane direction. The FTIR analysis of the samples conducted within the wavelength range of 1.4 to 25 µm, demonstrates a significant absorption value exceeding 90% in the entire whole mid-infrared and near-infrared regions. Notably, one of our samples demonstrates exceptional absorption across the entire terahertz practical band (0.3 to 3 THz), highlighting that the developed materials possess favorable characteristics making them an excellent option for terahertz applications. The findings of this work contribute to the understanding of the structural, electrical, and optical properties of these graphene-based materials and pave the way for their utilization in various fields
  9. Keywords:
  10. Reduced Graphene Oxide ; Characterization ; Electrical Properties ; Optical Absorption ; Wide-band Absorber ; Terahertz Applications

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