Van der waals epitaxial growth of mixed-dimensional 1D/2D heterostructures with tellurium nanowires and transition metal dichalcogenide nanosheets for nonlinear optical applications

One-dimensional (1D) tellurium (Te) nanowires (NWs) have triggered intense attention due to their remarkable properties in electronics, optoelectronics and nonlinear optics. However, the saturable absorption properties of Te NWs and the ability to be bleached by strong pulsed energy need to be further improved. Van der Waals (vdW) heterostructures based on two-dimensional (2D) transition metal dichalcogenides (TMDCs) exhibit prominent nonlinear optical properties. Direct epitaxial growth of large-area 1D/2D Te-TMDC vdW heterostructures is still rarely investigated. Herein, we demonstrate the controllable epitaxial growth of large-scale 1D/2D vertical Te-TMDC heterostructures via two-step vapor phase deposition method. Our experimental results have confirmed that the saturable absorption properties of as-prepared Te-TMDC heterostructures can be obviously enhanced. The first principle calculations and surface potential measurements demonstrate that effective interlayer charge transfer between Te NWs and TMDC nanosheets is beneficial for promoting the saturable absorption properties. Systematic investigation of vdW Te-TMDC heterostructures with nonlinear optical properties is vital for the next generation of nanophotonics and integrated photonics, which paves the way for the development of saturable absorbers and light modulators based on Te-TMDC vdW heterostructures.