2, University of Puerto Rico, San Juan, Puerto Rico, United States
Given their distinct structural and electronic properties, two dimensional materials, such as transition metal dichalcogenides (TMDs), have received increasing attention due to their potential applications in a new generation of 2D opto-electronics. Laterally connected TMD materials with distinct chemical composition can form heterostructures that are the building blocks for developing 2D p-n diodes, light-emitting diodes, photovoltaic devices, and transistors. A large scale and controlled growth of this kind of heterostructures is necessary to exploit the full potential of TMD materials. Here we report the successful synthesis of 2D heterostructures composed of bilayer and multilayer 2D semiconductor that are laterally connected (MoSe2-WSe2 and MoS2-WS2), via a modified Chemical Vapor Deposition (CVD) process. The proposed approach allows to in situ produce single- and multi-junction heterostructures by only changing the carrier gas supplied during the growth. For optimal growth conditions, the grown heterostructures can be found over large areas on the substrate surface. Raman and Photoluminescence spatial mapping confirm the chemical and optical homogeneity of the distinct TMD domains in the heterostructures. PL line scan revealed the effective modulation of the optical bandgap across the heterostructures, as well as the interfaces quality. The grown structures have great potential for developing 2D heterogeneous materials with higher degree of complexity such as superlattices and one-dimensional periodic quantum wells.