Epitaxial configuration of unidirectionally-aligned MoS2 monolayer on sapphire

Highly-oriented MoS2 monolayer (ML) on the sapphire(0001) substrate were grown by metal-organic chemical vapor deposition. The epitaxial configuration of ML-MoS2/sapphire has been studied using low-energy electron diffraction (LEED) combined with first-principles calculations. LEED analysis based on the dynamical diffraction theory revealed that the MoS2 ML is grown with the epitaxial relationship of MoS2 [11-20] // Al2O3 [11-20] and MoS2 [1-100] // Al2O3 [1-100], and that the formation of antiparallel (inversion) domains is effectively suppressed. The observed epitaxial relationship isinsensitive to the direction of surface steps on the sapphire substrate.