Scalable Epitaxial Synthesis of Two-Dimensional Transition-Metal Dichalcogenide Lateral Heterostructures

The integration of diverse semiconductor materials forms the foundation of modern electronic technologies. Two-dimensional lateral heterostructures (2DLHs)—where distinct 2D materials are seamlessly stitched within the same atomic plane—offer unique opportunities for novel electronic and optoelectronic devices. Despite significant progress in the synthesis of 2DLHs, the scalable synthesis of epitaxial 2DLHs remains a central challenge. In this dissertation, we present a patternable lateral epitaxy strategy that overcomes this limitation by enabling the spatially defined, epitaxial synthesis of 2DLHs at the wafer scale. First, we developed a clean, stamp-based patterning method capable of producing submicrometer features with atomically clean edges. Using these patterned edges as epitaxial templates, we demonstrated the lateral epitaxial growth of WS\textsubscript{2} from MoS\textsubscript{2} edges. This approach was further extended to multiple material systems—including WS\textsubscript{2}–WSe\textsubscript{2}, MoS\textsubscript{2}–WSe\textsubscript{2}, and MoS\textsubscript{2}–MoSe\textsubscript{2}—while preserving epitaxial registry despite lattice mismatches of up to 4\%. These results establish patternable lateral epitaxy as a generalizable strategy for spatially controlled 2DLH synthesis. We then investigate the growth mechanisms governing lateral epitaxy under diffusion-limited conditions. We show that operating in this regime produces a nucleation "dead zone" near patterned edges. We developed a quantitative 1D diffusion model that explains the observed growth kinetics and extracted a diffusion length of approximately 670~nm for the growth precursor. We also showed that diffusion-limited growth yields isotropic lateral growth rates independent of edge shape or crystal orientation, enabling heterojunctions with arbitrary geometries and uniform interface quality. Building on these insights, we achieved wafer-scale arrays of patterned, epitaxial 2DLHs and demonstrated their compatibility with standard nanofabrication processes for device integration. The resulting heterojunctions could serve as building blocks for functional electronic devices. Looking ahead, we propose several future directions to further advancing patternable lateral epitaxy and new material platforms such as metal–semiconductor 2DLHs, strain-engineered heterojunctions, and 2D molecular crystals. These efforts hold significant potential to unlock the novel 2D electronic and optoelectronic systems.