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dc.contributor.advisorGhosh, Arindam
dc.contributor.authorAparna, P
dc.date.accessioned2024-03-25T04:36:15Z
dc.date.available2024-03-25T04:36:15Z
dc.date.submitted2023
dc.identifier.urihttps://etd.iisc.ac.in/handle/2005/6453
dc.description.abstractLight-matter interaction of two-dimensional (2D) materials and their van der Waals hybrids have gained significant interest in the past few years as they offer an intriguing platform for studying fundamental physical phenomena and exploring potential technological applications. Owing to their excellent light absorption properties, semiconducting transition metal dichalcogenides (TMDC) are considered ideal for partnering with graphene to form a 2D hybrid for optoelectronic investigations. While the high photo-responsivity arising from the physical separation of photo-generated carriers across the hetero-interface has been the focus of optoelectronics investigations of graphene-TMDC-based heterostructures, understanding of the underlying mechanism that governs the inter-layer charge transfer process is limited, which is however essential for designing and developing advanced devices. In this thesis, we study the optoelectronics of graphene and TMDC-based heterostructures, mainly focusing on developing a comprehensive understanding of the physics that actuates the charge carrier transfer process and its dynamics at the heterostructure interface. In the first part of the thesis, we describe the temperature-dependent photo-response measurements on single-layer and bilayer graphene-TMDC heterostructure-based field effect transistors (FETs). We observe that the charge-transfer process is temperature dependent, and the energy scales defined by the band alignment at the interface govern the charge-transfer dynamics. The experiments also capture the role of TMDC trap states in the inter-layer charge transfer process. Furthermore, the performance figures of the graphene-TMDC van der Waals hybrid evaluated at room temperature suggest a higher bandwidth compared to many of its contemporary FET-based photodetectors, along with a significant gain. In the second half of the thesis, we have leveraged WSe2 proximitized twisted bilayer graphene (tBLG) to perform optoelectronic measurements, where the misorientation angle of the tBLG layer was chosen to lie close to the magic angle of 1.1○. We show that the photoresponse is extremely sensitive to the band structure of tBLG. Strong suppression of photoresponse is observed on tuning the Fermi energy inside the low energy moiré flat bands. However, as the Fermi level is tuned beyond the moiré bands, photo-gating-mediated photoresponse prevails. Our observations suggest that the screening effects from moiré flat bands strongly affect the charge transfer process at the WSe2/tBLG interface, which is further supported by time-resolved photo-resistance measurements. Finally, we present the low-frequency 1/f noise measurements performed on optically excited small-angle WSe2/tBLG heterostructures. The reduced screening inside the moiré band gap is manifested as an enhancement in noise magnitude, suggesting the sensitivity of noise measurements to the band structure of the underlying system.en_US
dc.language.isoen_USen_US
dc.relation.ispartofseries;ET00462
dc.rightsI grant Indian Institute of Science the right to archive and to make available my thesis or dissertation in whole or in part in all forms of media, now hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertationen_US
dc.subjectGrapheneen_US
dc.subjectOptoelectronicsen_US
dc.subjectLight-matter interactionen_US
dc.subjecttransition metal dichalcogenidesen_US
dc.subjectphotoresponseen_US
dc.subjectheterostructuresen_US
dc.subject.classificationResearch Subject Categories::NATURAL SCIENCES::Physicsen_US
dc.titleInvestigation of inter-layer charge transfer process in optically excited graphene and transition metal dichalcogenide-based heterostructuresen_US
dc.typeThesisen_US
dc.degree.namePhDen_US
dc.degree.levelDoctoralen_US
dc.degree.grantorIndian Institute of Scienceen_US
dc.degree.disciplineFaculty of Scienceen_US


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