Materials Science Research Lecture

Abstract: Atomically thin materials exhibit extraordinary physical properties based on their structure and composition, which will enable electronic devices with enhanced performance, mechanical flexibility, and increased functionality. To date, however, the study of 2D materials has focused primarily on sheets with structures derived from bulk, layered solids (e.g., graphene from graphite). Although successful thus far, this approach limits the field to a selected library of structures, thereby reducing the potential to engineer new properties in 2D materials. In this talk, I will discuss how the growth of entirely synthetic 2D materials—those without bulk analogues—dramatically expands our capability to engineer materials with novel properties.

Following a survey of foundational work concerning graphene and 2D silicon, I will focus on the first synthesis of 2D boron sheets (i.e., borophene), which we grow on a silver surface under ultra-high vacuum conditions. Atomic-scale imaging via scanning tunneling microscopy shows the growth of two borophene phases, both of which exhibit anisotropic structures based on a common bonding motif that is distinct from any bulk boron structure. Multiple techniques confirm that the borophene sheets are atomically thin and chemically discrete from the underlying substrate, which is consistent with a synthetic analogue to graphene. Moreover, unlike semiconducting bulk boron, borophene shows metallic characteristics. This systematic approach towards new 2D materials discovery can be generalized to explore a variety of elemental and compound structures which cannot be realized in bulk-derived layered crystals, thus providing a vast phase space for deterministic structure-property engineering.

Bio: Andrew Mannix earned his B.S. at the University of Illinois at Urbana-Champaign and his Ph.D. in Materials Science and Engineering at Northwestern University, advised by Prof. Mark Hersam and Dr. Nathan Guisinger of Argonne National Laboratory. He is currently a Kadanoff-Rice Postdoctoral Fellow in the James Franck Institute at the University of Chicago, where he works in the research group of Prof. Jiwoong Park on new methods for atomically-thin nanomaterials growth, processing, and assembly.