Clarissa Towle, University of California, Berkeley and Lawrence Berkeley National Laboratory
4D STEM Study of Au-Induced Epitaxial Strain in Few- and Monolayer MoS2
Written by Bharati Neelamraju
Associated with both UC Berkeley and Lawrence Berkeley National Lab (LBNL), most of Clarissa Towle’s work was done at LBNL using the four-dimensional (4D) scanning transmission electron microscope (STEM). Towle explains that this microscopy is 4D because the microscope scans a 2D array of 2D diffraction patterns of a given sample. She works on the epitaxial growth of gold on 2D transition metal dichalcogenides (TMDCs) to understand the role of strain on the top layer of a stack for opto-electronic device fabrications. Towle emphasized the fact that this technique uses about 2000 images or more to provide precise useful data. The researchers also use neural networks to increase the pace of their “Big Data” set analysis. They teach the neural network about the diffraction patterns of the gold on TMDCs. While the neural network gives the basic lattice diffraction peaks, it still does not understand all the nuances and says the same. Her excitement connected with the 4D STEM images and the data they have so far was contagious.