MSE Ph.D. Proposal – Meng-Yen Tsai
Prof. Eric Vogel, Advisor, MSE
Prof. Vladimir Tsukruk, MSE
Prof. Oliver Brand, ECE
Prof. Samuel Graham, MSE
Prof. Valeria Milam, MSE
Title: Materials Challenges of Two-Dimensional materials for Flexible Sensing Applications
Sensors are playing an increasingly important role in our lives because they are able to detect environmental changes and, therefore, initiate a response to these changes. Sensors convert detected physical or chemical changes, for example, motion, radiation, heat, acidity, chemicals, etc., to useful and readable signals. A field-effect transistor (FET), a semiconductor device in which the electrical current is controlled through an applied gate voltage, is promising for many sensing applications. Even though FETs-based sensors have been well-developed, flexible version of such sensors remains a big challenge and requires new materials and new sensing designs. Two-dimensional (2D) materials such as graphene and transition metal dichalcogenides are promising candidates for FET-based sensors due to their flexibility, transparency and potential for high electrical performance. Because of the atomically thin nature of 2D materials, their electrical properties are extremely sensitive to their atomic-scale structure as well as to their surfaces and interfaces with other materials. Specifically, defects, dopants, attached molecules or change in the band structure due to strain can shift the Fermi level resulting in a measured change in current. The goal of this research is to explore the use of 2D materials in FET-based sensors and develop a fundamental understanding of the impact of materials processing, structure, interfaces and surfaces on resultant electronic properties. The following first provides background information related to 2D materials including synthesis, structure, properties and their application to FET-based sensors. The research performed thus far is then described including the impact of molecular dopants and strain on transition metal dichalcogenides, and initial application of 2D materials to chemical, biological and strain sensors. Finally, a future research plan is presented.