Field-effect transistors on monolayer transition metal dichalcogenides synthesized by chemical vapor deposition
Since their discovery by Geim et al. in 2004, two-dimensional van der Waals materials (2DMs) have attracted wide research interest for their unique electronic, optical, and mechanical properties. These materials consist of stacked, atomically-thin sheets bonded by van der Waals forces. 2DMs are suited for electronic applications due to their superb transport properties and resistance to short channel effects, especially if a single sheet is isolated (monolayer). One family of 2DMs, known as transition metal dichalcogenides (TMDCs), are particularly useful as channel material in transistor devices due to their often-semiconducting properties. However, among the various challenges associated with applying TMDCs to conventional electronic devices, the most important by far is the small surface area of isolated monolayers. The synthesis of large-area, high-quality TMDC monolayers is an important research question in the advancement of this field towards industrialization. This thesis describes the creation of field-effect transistors based on pure and alloyed TMDC monolayers synthesized by chemical vapor deposition (CVD). First, different synthesis approaches are contrasted based on experimental results. Next, TMDC films with a variety of electronic properties are examined using microscopic and spectroscopic characterization methods. Finally, field-effect devices are fabricated and measured to demonstrate the transport capabilities and the device viability of CVD grown TMDCs. The work described here can be a step toward the design of industrial 2DM process technology and provides a demonstration of possible approaches to characterization and device integration of 2DMs.
2D materials, chemical vapor deposition, field-effect transistor
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign