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

Abstract

ABSTRACT Single‐crystalline molybdenum disulfide (MoS 2 ) 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 MoS 2 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 MoS 2 orientation when sapphire substrates are manufactured to semiconductor industry‐standard specifications and wafer size. Here, we report single‐crystalline MoS 2 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 MoS 2 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 MoS 2 monolayer forms through recrystallization of 60°‐oriented domains during and after MoS 2 monolayer coalescence. As a result, single‐crystalline 1.1 MoS 2 monolayer exhibits carrier mobilities of 30 ± 5 cm 2 V −1 s −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.