{"604816":{"#nid":"604816","#data":{"type":"event","title":"PhD Proposal by Neha Kondekar","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003ETHE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EGEORGIA INSTITUTE OF TECHNOLOGY\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EUnder the provisions of the regulations for the degree\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003EDOCTOR OF PHILOSOPHY\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003Eon Tuesday, April 24, 2018\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E3:00 PM\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cstrong\u003Ein MRDC 3515\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E\u0026nbsp;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003Ewill be held the\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E\u0026nbsp;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EDISSERTATION\u003C\/strong\u003E\u003Cstrong\u003E\u0026nbsp;PROPOSAL\u003C\/strong\u003E\u0026nbsp;\u003Cstrong\u003EDEFENSE\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cstrong\u003Efor\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ENeha Kondekar\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026quot;\u003Cstrong\u003EInvestigation of transformations in transition metal dichalcogenides during synthesis and operation of devices\u003C\/strong\u003E\u003Cstrong\u003E\u0026quot;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ECommittee Members:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Matt McDowell, Advisor, MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Eric Vogel, MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Faisal Alamgir, MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Mark Losego, MSE\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EProf. Satish Kumar, ME\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E\u0026nbsp;\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EAbstract:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ETransition metal dichalcogenides (TMDCs) are promising candidates for electronics and energy storage devices. Materials such as MoS\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;have been used for next-generation transistors, photosensors, electrocatalysts, and electrodes for Li-ion batteries. The highly anisotropic crystal structure of TMDCs features chemically active edge sites and relatively inert basal planes, which are bonded by weak Van der Waals forces. Careful control of the crystallographic orientation, composition, and layer thickness of TMDCs is critical to yield different electronic, chemical and optical properties. While obtaining uniform TMDC growth over large areas is necessary for commercialization of electronic devices, maximizing the fraction of edge sites exposed to the surface is thought to be required for enhancing catalytic activity. Thus, understanding the parameters that control structural properties of TMDC crystals is necessary for future applications.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EBeyond controlling structural and electronic properties during synthesis of TMDCs, it is also critical to understand how structural and chemical properties of TMDC interfaces impact behavior in applications. For instance, interfacing TMDC layers with different metals and semiconductors is necessary for virtually all applications. Au and Pd are commonly used as metallic contacts in MoS\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;transistors, which in turn are fabricated on Si or Ge wafers. In hydrodesulfurization catalyst materials used to extract sulfur from petroleum feedstock, Ni species are dispersed on the surface of MoS\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;crystals. Ni-promoted MoS\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;also serves as a cheap alternative to Pt for catalyzing the hydrogen evolution reaction (HER) during water splitting. The properties of TMDC heterointerfaces and the evolution of these interfaces under device operating conditions require dedicated further study to enable optimal performance.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003E\u003Cem\u003EThe primary research objective of this proposed work is to understand and control the structural and chemical transformations within MoS\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;and at its heterointerfaces both during synthesis and during operation of electronic\/energy devices\u003C\/em\u003E\u003C\/strong\u003E\u003Cstrong\u003E.\u003C\/strong\u003E\u0026nbsp;Several\u0026nbsp;\u003Cem\u003Ein-situ\u003C\/em\u003E\u0026nbsp;and\u0026nbsp;\u003Cem\u003Eex-situ\u003C\/em\u003E\u0026nbsp;characterization techniques will be used to investigate structural\/chemical transformations. Preliminary results using\u0026nbsp;\u003Cem\u003Ein-situ\u003C\/em\u003E\u0026nbsp;X-ray photoelectron spectroscopy (XPS) show that the chemical transformations at MoS\u003Csub\u003E2\u003C\/sub\u003E\/metal interfaces are dictated not only by the chemical reactivity of the interfaced material but also by the crystallographic orientation of MoS\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;layers. This is attributed to different chemical and electronic properties of edge sites compared to basal planes in MoS\u003Csub\u003E2\u003C\/sub\u003E. These results suggest that careful control over the structure of interfaces is necessary for optimal charge transport in MoS\u003Csub\u003E2\u003C\/sub\u003E-based transistors and other electronic devices. Building on this understanding of interfacial chemistry, the proposed future work includes evaluating and improving the performance of TMDC electronic devices by controlling the structural and chemical configuration at the material-MoS\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;interface. Furthermore, TMDC devices often experience elevated temperature during fabrication\/processing, and the extent of interfacial transformations will be studied as a function of temperature. Finally, the influence of metal additions on the evolution of MoS\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;crystals during synthesis will be investigated with\u0026nbsp;\u003Cem\u003Ein-situ\u003C\/em\u003E\u0026nbsp;methods. This proposed research is important because it will identify factors that currently limit the performance of TMDC-based devices.\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"\u0022Investigation of transformations in transition metal dichalcogenides during synthesis and operation of devices\u0022"}],"uid":"27707","created_gmt":"2018-04-06 16:06:08","changed_gmt":"2018-04-06 16:06:08","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2018-04-24T16:00:00-04:00","event_time_end":"2018-04-24T18:00:00-04:00","event_time_end_last":"2018-04-24T18:00:00-04:00","gmt_time_start":"2018-04-24 20:00:00","gmt_time_end":"2018-04-24 22:00:00","gmt_time_end_last":"2018-04-24 22:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"102851","name":"Phd proposal"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78771","name":"Public"},{"id":"174045","name":"Graduate students"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}