Time-Resolved Growth of 2D WSe₂ Monolayer Crystals

Understanding and controlling the growth evolution ofatomicallythin monolayer two-dimensional (2D) materials such as transition metaldichalcogenides (TMDCs) are vital for next-generation 2D electronicsand optoelectronic devices. However, their growth kinetics are notfully observed or well understood due to the bottlenecks associatedwith the existing synthesis methods. This study demonstrates the time-resolvedand ultrafast growth of 2D materials by a laser-based synthesis approachthat enables the rapid initiation and termination of the vaporizationprocess during crystal growth. The use of stoichiometric powder (e.g.,WSe2) minimizes the complex chemistry during the vaporizationand growth process, allowing rapid initiation/termination controlover the generated flux. An extensive set of experiments is performedto understand the growth evolution, achieving subsecond growth aslow as 10 ms along with a 100 & mu;m/s growth rate on a noncatalyticsubstrate such as Si/SiO2. Overall, this study allows usto observe and understand the 2D crystal evolution and growth kineticswith time-resolved and subsecond time scales.