2, University of Dayton, Dayton, Ohio, United States
The development of new processing schemes that enable 2D materials to be incorporated on soft, organic substrates remains a fundamental challenge for future flexible electronics based on the unique layered structures. Local, transient heating and patterning of amorphous precursors by laser processing may be the key to unlocking the unique attributes of flexible 2D material systems. Initial experiments reveal the successful phase transformation of amorphous transition metal dichalcogenides (TMD) including MoS2 and WS2 deposited by physical vapor deposition (PVD) on stretchable polymer substrates to their crystalline van der Waals layered structures. Detailed kinetic studies of crystal formation were accomplished via high throughput in-situ Raman spectroscopy at different surface temperatures and environmental conditions. With this technique, heterostructures were formed incorporating multiple TMD layers that were annealed simultaneously, and insights into the role of surface diffusion and activation energy for crystallization will be discussed. Additionally, large area, wafer-scale crystallization of 2D materials on flexible substrates with the use of a broadband pulsed lamp source demonstrate the potential for optical annealing at multiple length scales for ease of manufacturing directly on soft substrates.