CVD Grown Hybrid MoSe$_2$-WSe$_2$ Lateral/Vertical Heterostructures with Strong Interlayer Exciton Emission

TL;DR

This paper reports a scalable CVD method to synthesize hybrid MoSe₂-WSe₂ heterostructures with strong interlayer exciton emission, enabling advanced studies and applications of 2D quantum materials.

Contribution

The authors developed a controlled CVD synthesis technique for lateral and hybrid heterostructures of MoSe₂ and WSe₂ with tunable dimensions and high optical quality.

Findings

Strong interlayer exciton emission observed at 4 K and room temperature.

Heterostructure type and size can be tuned by growth parameters.

High optical quality demonstrated through spectroscopic and microscopic analyses.

Abstract

Lateral heterostructures of 2D transition metal dichalcogenide offer a powerful platform to investigate photonic and electronic phenomena at atomically sharp interfaces. However, their controlled engineering, including tuning lateral domain size and integration into vertical van der Waals heterostructures with other 2D materials, remains challenging. Here, we present a facile route for the synthesis of two types of heterostructures consisting of monolayers of MoSe$_2$ and WSe$_2$ - purely lateral (HS I) and hybrid lateral/vertical (HS II) - using liquid precursors of transition metal salts and chemical vapor deposition (CVD). Depending on the growth parameters, the heterostructure type and their lateral dimensions can be adjusted. We characterized properties of the HS I and HS II by complementary spectroscopic and microscopic techniques including Raman and photoluminescence spectroscopy, and optical and atomic force microscopy, and scanning electron and transmission electron microscopy. The photoluminescence measurements reveal strong interlayer exciton emission in the MoSe$_2$/WSe$_2$ region of HS II, which dominates the spectrum at 4 K and persisting up to room temperature. These results demonstrate high optical quality of the grown heterostructures which in combination with scalability of the developed approach paves the way for fundamental studies and device applications based on these unique 2D quantum materials.