CVD growth and optical characterization of homo and heterobilayer TMDs

The stacking of few layers of transition metal dichalcogenides (TMDs) and their heterostructures allows us to create new structures, observe new physical phenomena, and envision new applications. Moreover, the twist angle in few-layer TMDs can significantly impact their electrical and optical properties. Therefore, controlling the TMD material and obtaining different stacking orientations when synthesizing TMDs via chemical vapor deposition (CVD) is a powerful tool, which can add functionality to TMD-based optoelectronic devices. Here, we report on the synthesis of few-layer MoS2 and WS2 crystals, as well as their heterobilayer structures with 0 & DEG; and 60 & DEG; twist angles between layers via CVD. Raman and photoluminescence spectroscopies demonstrate the quality, crystallinity, and layer count of our grown samples, while second harmonic generation shows that adjacent layers grow with 0 & DEG; or 60 & DEG; twist angles, corresponding to two different crystal phases. Our study based on TMDs with different and multiple stacking configurations provides an alternative route for the development of future optoelectronic and nonlinear optical devices.