on h-BN by Chemical Vapor Deposition*

Transition metal dichalcogenides (TMDCs) exhibit electronic properties that drastically change in the monolayer limit, sensitive phase transitions, and other unique features, spurring interest in device-scale integration of these materials. However, scalable and reproducible synthesis of these materials has proven challenging. Previous works have stressed the impact of synthesis parameters, including relative precursor concentrations, carrier gas species, pressure, temperature, and humidity, on the type, quality, and quantity of material synthesized. Here, we employ a chemical vapor deposition (CVD) conversion process to synthesize tungsten disulfide (WS₂) crystals atop exfoliated hexagonal boron nitride (h-BN) crystals. The products of these syntheses were characterized with atomic force microscopy, scanning electron microscopy, and Raman microscopy. These results yield insights into CVD conversion as an avenue for next-generation electronics and direct growth of vertical van der Waals heterostructures.