The heterogeneities such as defects and dopants can give rise to exotic electronic properties in 2D transition metal dichalcogenides (TMDs), but to this date, there is no detailed study to illustrate how heterogeneities can be engineered to tailor their thermal properties. Here, through combined experimental and theoretical approaches, we have explored the effect of defects, doping, and metal isotopes on the thermal transport of monolayer 2D TMDs grown by chemical vapor deposition (CVD). We found that doping and defects in a CVD-grown monolayers 2D crystals can significantly affect their thermal conductivity due to the mass induced kinetic energy and potential energy difference. Furthermore, we find the isotopically pure monolayer 2D crystals synthesized by CVD can significantly boost their in-plane thermal conductivity resulting from combined effects of the reduced isotope disorder and a reduction in defect-related scattering. Our work demonstrates that heterogeneity engineering can effectively tune the thermal conductivity of 2D TMDs, which is important for thermal properties development and thermal management in 2D electronic and optoelectronic building blocks.
Synthesis science was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division. Characterizations were performed at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.