TRANSMISSION ELECTRON MICROSCOPY OF STRUCTURAL DISORDER IN TWO-DIMENSIONAL MATERIALS

Transmission electron microscopy (TEM) of two-dimensional materials (2D) offers an unprecedented opportunity to study disordered systems down to the single-atom level. The reduced dimensionality of these systems provides a two-fold opportunity: first, 2D materials serve as model systems for exploring direct correlations between the structure and properties of individual atomic features. Second, these studies enable the development of new 2D materials and devices with precisely tailored optical, electronic, and mechanical properties. The experiments presented in this thesis show the first atomic-resolution images of extended one- and two-dimensional disorder in 2D materials and the extraordi-nary range of consequences they have on the local materials properties. The thesis begins with studies that probe the structure and properties of the 1D defects that make up grain boundaries in atomically-thin layers of graphene and molybdenum disulfide. These experiments span length scales across five orders of magnitude to image every atom at the grain boundaries through atomic-resolution scanning TEM and rapidly map the location, orientation, and shape of severa