Extended Data Fig. 9: Etching behavior of epitaxially and hypotaxially grown 1L-MoS2.
From: Hypotaxy of wafer-scale single-crystal transition metal dichalcogenides
SEM images of a, epitaxially grown MoS2 on a c-sapphire substrate and b, hypotaxially grown MoS2 at 1000 °C after annealing at 1000 °C under low pressure of <10−3 Torr. The mild etching processes are widely used to visualize grain boundaries and determine crystalline orientation33,34,35,36. The SEM images were taken from different regions to investigate crystalline orientation of large area. The epitaxially grown 1L-MoS2 showed two triangular etched regions with opposite directions (indicated by red and yellow dashed lines) due to presence of grains with 0° and 60° orientations on the c-sapphire substrate as shown in (a). Meanwhile, the hypotaxially grown MoS2 exhibited unidirectional triangular shapes as shown in (b), indicating that the entire area etched by vacuum annealing is unidirectionally oriented.
