Investigations of 2D Materials Towards THz Source and Detector Applications

Date

2024-3-08

Author

Aytekin, Yusuf Samet

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The work investigates static and dynamic properties of 2D materials, graphene to transition metal dichalcogenides, for their possible use as a Terahertz source or detector. The static properties in THz domain were carried out with Time-Domain THz Spectroscopy (THz-TDS), while dynamic properties were investigated via Time-Resolved Terahertz Spectroscopy (TRTS) systems. The initial part of the studies was optimization of the terahertz systems thus after the optimizations the bandwıdth was expanded and S/N have been improved at maximum terahertz amplitude. The systems were used to measure the static and dynamic properties of 2D materials. The single-layer graphene (SLG) on various substrates were monitored to check the polymer substrates and growth/transfer effects on graphene. The multilayer graphene (MLG) samples on polymer and quartz substrates were investigated. Finally, the transition metal dichalcogenide samples were also analysed. The investigation of the static properties of the samples and the substrates showed low insertion losses for polymers compared to semiconductor or quartz substrates. The dynamic responses of SLG samples on polymer substrates showed a metallic-like property, as fast initial rise (carrier generation and quick decay of the observed THz response. Unlike the SLG on polymer samples, the SLG grown/transferred on semiconducting samples revealed a rather weak response dominated by the substrate responses making the extraction of graphene response rather difficult. MLG samples, however, showed an increased THz photoconductivity upon optical excitation with 400nm and 800nm light. TMDC samples of MoSe2/PtSe2 and WSe2 were studied for their THz conductivity properties as a high mobility candidate for plasmon resonance amplification of terahertz radiation. The responses of both samples upon optical excitation with 400nm adn 800nm light showed a fast initial rise and very fast decay for their potential use as high-speed applications requiring fast and reliable switching.

Subject Keywords

2D materials, Transition Metal Dichalcogenides, Graphene, Time-Resolved Terahertz Spectroscopy, Optical Pump Terahertz Probe Spectroscopy

URI

https://hdl.handle.net/11511/109431

Collections

Graduate School of Natural and Applied Sciences, Thesis