Obtaining 2D Semiconductors

• Blake Kiefer, Biochemistry, Washington & Jefferson College

• Chitraleema Chakraborty, Materials Science and Engineering, University of Delaware

The ‘Scotch Tape Method’ of mechanical exfoliation was first used to isolate single-atom thick layers of graphene from bulk graphite. This increased the interest in possible applications for the exotic physical properties of single-layered materials, or monolayers, which differ from the properties of the corresponding multi-layered bulk forms. ¹ In fact, each possible number of layers within a material will result in physical properties that are unique and not exhibited in any other amount of layering of that material including its monolayer form.  However, the physical differences exhibited between different amounts of layering are more obvious within the material at fewer numbers of layers and diminishes as thickness increases. Our group’s interest involves two-layered bilayers.  Specifically, twisted 2D-bilayers whose 2D-monolayer components are rotated at various angles relative to one another to assess how this alters the bilayer’s magnetic properties. Mechanical exfoliation is used to acquire the monolayer components used in constructing each twisted bilayer sample. After a monolayer is obtained, it is divided into two portions that are vertically stacked upon one another in a desired fashion. Because this process is done manually, the exfoliated monolayers must be of a large area (≥ 20 µm) to produce stackable portions that are each still of sufficient size to handle with our devices.  Therefore, in this poster we seek to optimize the process of mechanical exfoliation with the TMDC WSe₂ to increase our chances of obtaining a supply of large-area monolayers consistently for experimenting with.