2D Materials: Synthesis, Characterization, and Applications

The isolation of monolayer graphene by Andre Geim and Konstantin Novoselov in 2004 created an explosion of layered materials research in the fields of condensed matter physics, material science, electrical engineering, chemistry, and nanobiology, to name a few. The applications have been broad from enhancing electrode performance in batteries to gas sensing to high-frequency analog flexible electronics. For several years and still to this day, graphene has provided a fertile ground for research due to its superior properties. However, failed efforts to engineer a substantial bandgap, a requirement for digital electronics, led researchers to look elsewhere in the periodic table for other layered materials with rich physics and an even broader application space. Fortunately, the technical expertise developed in the graphene system could, for the most part, be leveraged and modified in these new material systems. This thesis presents a brief history of the field of two-dimensional electronics. The rediscovery - and it can only really be characterized as such since most of these materials were studied in the bulk form going back to the 1960s - of these two-dimensional materials with properties ranging from superconductivity, piezoelectricity, optical and electrical anisotropy, and large magnetoresistivity required the development of new characterization techniques to address the perturbations that accompanied the “thinning” of layers. Several characterization techniques were developed and are presented in this thesis. Moreover, in an effort to push these materials closer towards technological viability, synthesis techniques were developed that enabled the systematic study of a prototypical material system, molybdenum disulfide (MoS₂), in order to address the challenges that accompany scalability and determine the structure-property-function relationship.