This Ph.D. dissertation presents two novel approaches in the field of materials science and nanotechnology. The first part introduces an integrated photodetector design that combines a two-dimensional material, MoS2, with plasmonic structures. Nanoantenna arrays (NAs) are positioned above and below the MoS2 layer to enhance the electric field, reducing the gap between the NA layers to the nanometer scale. The fabrication process of the NAs/MoS2/NAs photodetector is detailed, encompassing the transfer of MoS2 nanosheets, patterning of NAs, and alignment of the top layer NAs. The characterization of the fabricated photodetector includes the morphology analysis of MoS2, Raman spectrum evaluation, and scanning electron microscope imaging. Finite difference time domain (FDTD) simulations investigate the plasmonic enhancement mechanism, revealing the distribution of electric field enhancement and absorption for different incident light polarizations. The results demonstrate a significant local electric field enhancement at the nanoantenna interface, with an enhancement factor of up to 25. These findings substantiate the potential of the proposed integrated photodetector for enhanced optical field and absorption, which can be leveraged in photodetection and nonlinear optical processes.The thesis then investigates the electrical characterization of MoS2-based photodetectors, focusing on photosensitivity and optimization parameters. Experimental measurements of photoconductivity, resistance, and photocurrent under laser-on and laser-off conditions reveal increased photosensitivity with laser power and applied bias voltage. By incorporating NAs on the top and bottom, the electron-hole pair generation is enhanced and resistance is reduced. Moreover, intentional adjustments are made to increase the lateral distance and size of the NAs to specifically focus on the nanoscale vertical gap and eliminate the lateral gap effect during the experiment. The study identifies the optimized conditions for high net photocurrent and minimal power consumption. The NAs/MoS2/NAs device exhibits the highest responsivity among the tested devices, providing insights into the electrical characteristics of MoS2-based photodetectors. Next, the thesis explores the nonlinear absorption behavior of NAs integrated devices, in bare MoS2, NA/MoS2, and NA/MoS2/NA layouts. Hyperspectral stimulated Raman scattering (hsSRS) imaging is employed to investigate the impact of the layered nanostructure on nonlinear absorption. Experimental results reveal distinct absorption characteristics in bare MoS2, NA/MoS2, and NA/MoS2/NA regions for various beam separation times. The double-layered NA/MoS2/NA structure exhibits the strongest two-photon absorption (2PA) and demonstrates the influence of pulse timing on the nonlinear absorption process. The exceptional nonlinear optical properties observed in the NA/MoS2/NA structure make it a promising candidate for various applications, including near-infrared detection, energy harvesting, and spectroscopy of organic materials. On the second part of the dissertation, a novel technique called reactive pulsed laser deposition of SiC is introduced, enabling precise and controlled deposition of large amount of SiC particles. The technique utilizes a pulsed laser to generate a localized hot spot on a target source, leading to the ejection of sillicon (Si) and carbon (C) atoms towards a substrate through laser-induced plasma expulsion. The ejected atoms combine to form SiC nanoparticles, which condense onto the substrate surface, allowing for selective local processing and pre-patterned shape printing. The fabricated SiC particles exhibit interesting photoluminescent properties and enable the fabrication of a diode with distinct current rectification behavior. The experimental results demonstrate the effectiveness of the reactive pulsed laser deposition technique in achieving controlled SiC deposition, showcasing its potential for advancing SiC-based electronic devices and structures. This Ph.D. thesis contributes to the understanding of integrated photodetectors, nonlinear optical effects, and precise material deposition techniques. The findings pave the way for enhanced optical field and absorption in photodetection, nonlinear optical processes, SiC-based devices, and offer opportunities for various research fields.
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