Real-time growth and structural dynamics study of 2D material heterostructures by in-situ low-energy electron microscopy
Abstract: Structural control at the atomic scale is crucial for designing the material properties of supported nanoscale systems for various technological applications, including micro- and optoelectronics, chemical sensing, and (photo)electrocatalysis, particularly in the case of supported, low-dimensional van der Waals materials. Generally, the properties of these loosely coupled materials are highly dependent on the precise number of layers and their interaction with the substrate, which can lead to dramatic changes in, e.g., electronic band structure and chemical as well as magnetic properties, which in turn may give rise to the emergence of intriguing yet poorly understood correlation phenomena such as, e.g., unconventional superconductivity and Mott transitions coupled with charge density waves.
Whereas the most commonly employed preparation method involves exfoliation from bulk materials and subsequent transfer onto a selected support, this approach is not easily scalable and is also known to introduce contamination into the material system, complicating (if not impeding entirely) the pursuit of a deeper understanding of the complex interplay between materials preparation, atomic structure, and the resulting properties. Ideally, such knowledge could be applied in a rationally designed, bottom-up synthesis process, providing an effective means to control the nanomaterials’ characteristics.
In this presentation, we discuss our recent efforts to grow and modify so-called two-dimensional (2D) materials on single-crystal transition metal substrates. Using the popular archetypical systems graphene/ruthenium [1, 2] and MoS2/gold [3, 4] as prominent examples, we demonstrate how the use of in situ, real-time low-energy electron microscopy and micro-diffraction, and spatially resolved spectroscopies can effectively reveal favorable conditions for the controlled synthesis of well-ordered single layers and the adaptation of their properties by, e.g., exploiting substrate symmetry, controlled intercalation of foreign elements, or even the dynamics of thermal annealing in the formation of MoSe2/graphene heterostructures [5]. Finally, we will showcase how our methodological approach can also shed light on the preparation of the elusive 1T phase of TaS2 [6].
References
[1] P. W. Sutter, J. I. Flege, and E. Sutter, Nature Mater. 7, 406 (2008)
[2] L. Buss et al., Carbon 231, 11960 (2025)
[3] M. Ewert et al., Front. Phys. 9, 654854 (2021)
[4] M. Ewert et al., ACS Appl. Nano Mater. 5, 17702 (2022)
[5] L. Buss et al., Ultramicroscopy 250, 113749 (2023).
[6] L. Buss et al., submitted.
Research Interests
My primary research focuses on developing functional materials via atomic layer deposition and reactive molecular beam epitaxy, targeting fundamental studies and applications in microelectronics, heterogeneous catalysis, energy storage and conversion, and chemical sensing. The main emphasis is on unraveling the structure-function relationship using in-situ and/or operando characterization during the growth or modification of (i) two-dimensional van der Waals materials and their heterostructures for applications in nanoelectronics and spintronics, and (ii) strongly correlated mixed metal oxide ultrathin films and nanostructures for CO2 conversion and chemiresistive microsensors integrated into the silicon CMOS platform. Additional areas of research include materials and process characterization in lithium and sodium ion batteries and functionalized perovskites for next-generation photovoltaics.
These research areas closely align with the research topics of the Institute for Matter and Systems at GATECH, likely sharing the most overlap with the Center for Organic Photonics and Electronics and other facilities.