Chemical Vapor Deposition for the Fabrication of WTe2/h-BN Heterostructures

Tungsten ditelluride (WTe₂) is a transition metal dichalcogenide with exotic properties, such as the quantum spin Hall effect, which has been demonstrated in monolayer WTe₂ heterostructures with h-BN. So far, these studies have relied on heterostructure fabrication via exfoliation, while direct growth methods to produce high-quality 2D WTe₂ on hexagonal boron nitride remain a challenge. Systematic studies of chemical vapor deposition (CVD) using NaCl as a seeding promoter are reported to produce WTe₂ crystals with different morphologies on Si/SiO₂ and Si/SiO₂/h-BN (exfoliated flakes or CVD monolayer) substrates. The formation of vertical WTe₂/h-BN heterostructures can be achieved by using a slightly increased growth temperature as compared to SiO₂ substrates, and characterization, including Raman and XPS studies, confirms the successful growth of high-quality WTe₂ on h-BN. This is further verified by magnetotransport measurements at low temperatures.