CVD Grown Hybrid MoSe ₂ –WSe ₂ Lateral/Vertical Heterostructures With Strong Interlayer Exciton Emission

ABSTRACT Lateral heterostructures (LHSs) of 2D transition metal dichalcogenides (TMDs) 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 (HSs), consisting of monolayers (MLs) 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 its 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 (PL) spectroscopy, optical and atomic force microscopy (AFM), and scanning and transmission electron microscopy (TEM). The PL measurements reveal strong interlayer exciton (IE) emission in the MoSe 2 /WSe 2 region of HS II, which dominates the spectrum at 4 K and persists up to room temperature (RT). These results demonstrate high optical quality of the grown HSs, which in combination with the scalability of the developed approach, pave the way for fundamental studies and device applications based on these unique 2D quantum materials.