2D Material Integration with Integrated Photonics: Waveguides, Micro-ring Resonators and Photodetectors Open Access
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This thesis reports research that exploits the strong light-matter interaction by the integration of the two-dimensional (2D) materials like transition metal dichalcogenides (TMDCs), for example, Molybdenum Ditelluride (MoTe2), Molybdenum Disulfide (MoS2) and Hexagonal Boron Nitride (hBN), with photonic devices like waveguides and micro-ring resonators (MRRs). The TMDC materials play a significant role in changing the effective refractive index (ng) and light absorption loss (κ) of the photonic devices, which can be engineered for development and advancement of optoelectronic devices and applications.The first study of the thesis was to experimentally characterize the effect of heterogeneous integration of TMDCs with silicon integrated photonic devices at 1550 nm wavelength. The experiments performed shows the change in refractive index and optical loss with change in the length and thickness of the TMDCs covering the devices (waveguides and micro-ring resonators).The thesis reports research that proceeded with designing and fabrication of photodetectors by using MoTe2 as the active material integrated with waveguides and micro-ring resonators. The material, after integration, was probed with two terminal transport measurements using electrical contacts to analyze the responsivity and dark current of the device. The design of contact pads was based on the image mapping of the TMDC flake on the device.Lastly, the thesis also covers the fabrication of waveguides and grating couplers using silicon nitride. The development of this platform is to design devices, which can operate in the visible spectrum (here at = 640 nm) and observe the effect of TMDCs at the excitonic wavelength of the material. The linear grating couplers were designed to enable coupling light from a free space Gaussian laser beam (640 nm) into the waveguides. Furthermore, the thesis also discusses the methodology used for integrating the TMDCs with the photonic devices, and all the optimizations made to the experimental setup for making it possible. The tools and services utilized, and challenges faced throughout the processes like 2D material transfer, Nanofabrication processes, and tools, availability of resources and official processing times for requests of orders making this research success, are briefly addressed at the end.