Phase-Engineered Field-Effect Transistors Based on Two-Dimensional Transition Metal Dichalcogenides
2020-08
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
Phase-Engineered Field-Effect Transistors Based on Two-Dimensional Transition Metal Dichalcogenides
Authors
Published Date
2020-08
Publisher
Type
Thesis or Dissertation
Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDCs) are layered materials in which each unit consists of a transition metal (Mo, and W) layer sandwiched between two chalcogen (S, Se, and Te) atomic layers. They can exist in either a semiconducting or metallic phase. Semiconducting TMDC based field-effect transistors (FETs) are considered promising candidates for post-Si electronics owing to their ultra-thin body enabling ultimate scalability. However, the large contact resistance at the metal/TMDC interface limits their drive current for high-performance applications. The large contact resistance is due to an enlarged schottky barrier height resulting from strong fermi-level pinning and the existence of van der Waal gaps at the metal/TMDC interface and in-between TMDC layers. The ultimate solution to the contact issue is to utilize lateral metallic-semiconducting TMDC junctions as 2D edge contacts. Thanks to the small free energy difference between its semiconducting 2H and metallic 1T’ phases, lateral 2H/1T’ MoTe2 homojunctions can be synthesized in situ by flux-controlled phase engineering. In this dissertation, a comprehensive study combining detailed structural and electrical properties of in-situ-grown lateral MoTe2 homojunctions formed via the flux-controlled technique is presented. MoTe2 p-MOSFETs with phase-engineered 1T’ contacts which showed significantly improved performance over devices with metal/2H contacts are demonstrated. In order to employ this flux-controlled technique for large-scale CMOS fabrication, a two-step lithographic synthesis approach for creating various lateral TMDC junctions is developed. Lateral 2H/1T′ MoTe2 homojunction p-MOSFETs and 2H-MoS2/1T′-MoTe2 heterojunction n-MOSFETs are fabricated using the two-step approach. Besides, a reversible phase transition between 2H and 1T’ MoS2 by gate-controlled Li+ intercalation through a solid PEO:LiClO4 electrolyte is demonstrated, which could allow the use of lateral metallic-semiconducting TMDC junctions for phase-change memory applications.
Description
University of Minnesota Ph.D. dissertation. August 2020. Major: Electrical/Computer Engineering. Advisor: Steven Koester. 1 computer file (PDF); xii, 179 pages.
Related to
Replaces
License
Collections
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
Ma, Rui. (2020). Phase-Engineered Field-Effect Transistors Based on Two-Dimensional Transition Metal Dichalcogenides. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/224983.
Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.