Recrystallization-Driven Formation of Single-Crystalline MoS₂ by Metal-Organic Chemical Vapor Epitaxy

Single-crystalline molybdenum disulfide (MoS₂) emerges as a leading n-type channel material for high-performance electronic devices in the angstrom era of computing. Chemical vapor epitaxy of single-crystalline MoS₂ relies on sapphire template engineering to impose a preferred crystalline orientation. A challenge of these approaches is to control the within-wafer statistical variance of the MoS₂ orientation when sapphire substrates are manufactured to semiconductor industry-standard specifications and wafer size. Here, we report single-crystalline MoS₂ on sapphire by metal-organic chemical vapor deposition (MOCVD), a mainstream semiconductor manufacturing method, without relying on template-engineering. By lowering the precursor adsorption rate in the mass-transport-limited reaction regime, the MoS₂ nucleation and growth rate slows sufficiently to favor epitaxy, initially with 0° and 60°-oriented crystals. Although a minority of 60°-oriented crystals deposit, a single-crystalline MoS₂ monolayer forms through recrystallization of 60°-oriented domains during and after MoS₂ monolayer coalescence. As a result, single-crystalline 1.1 MoS₂ monolayer exhibits carrier mobilities of 30 ± 5 cm²V^-1s^-1 in transistors fabricated through a 300 mm bonding-to-wafer route. Recrystallization during chemical vapor epitaxy presents a key mechanism to modulate crystal defect structures in transition metal dichalcogenides and is compatible with both bonding-to-wafer and monolithic integration approaches.