Chemical Vapor Deposition of Two-Dimensional Heterostructures

Two dimensional (2D) materials such as transition metal dichalcogenides (TMDs) are being
studied for their potential applications in opto-electronics, given their distinct structural and
electro-optical properties. Laterally stacked TMD heterostructures are crucial components for
constructing p-n junctions, light-emitting diodes, photovoltaic devices, and tunneling transistors. A
large scale and controlled growth of these lateral heterostructures is necessary to exploit the
TMDs potential for applications in flexible nanoelectronics. The objective of this research was to
optimize the growth of laterally connected semiconducting MoSe₂-WSe₂ and MoS₂-WS₂ bilayer
heterostructures, using the Chemical Vapor Deposition (CVD) technique. This synthesis method is
relatively simple, and allows the fabrication of single and multiple junction heterostructures with
the change of the carrier gas supplied during growth. Through Raman and Photoluminescence
characterization, the heterostructure samples were examined to confirm chemical composition,
structural homogeneity, and distinguishable interfaces of the TMDs heterojunctions. The optimal
conditions for the bilayer growth of MoSe₂-WSe₂ and MoS₂-WS₂ heterostructures were established
and the growth was repeated to corroborate effective replication.