Insight into the growth behaviors of MoS2 nanograins influenced by step edges and atomic structure of the substrate

Large-area single-crystal TMD growth modulated by sapphire substrates

“…Due to the twofold symmetry of the a-plane sapphire, the diffusion barriers along the step and across the step directions are distinct, which results in the growth of materials that exhibit anisotropy. [78][79][80]94 In addition, the a-plane sapphire is a nonpolar surface and the growth on the non-polar surface can make the luminescence efficiency increase, which provides ideas for device luminescence efficiency improvement.…”

“…They concluded that the increased oxygen content on the substrate surface after oxygen treatment decreases the diffusion barrier of the nanoparticles, which promotes the migration and agglomeration of MoS 2 nanoparticles. 94 Although the sapphire structures annealed in air and hydrogen at 900 °C are different, the stable ffiffiffiffiffi 31 p  ffiffiffiffiffi 31 p R9°surface is not affected by the annealing gases when the annealing temperature is increased above 1200 °C, and this reconstructed surface is stable in air, oxygen, hydrogen or vacuum. Liu et al thermally decomposed NH 4 HSO 3 to grow MoS 2 and then annealed MoS 2 at 1000 °C in different atmospheres.…”

“…10e and f). 94 Annealing of the grown sapphire results in the formation of triangular etching holes on MoS 2 when the annealing temperature exceeds a threshold. 116 Due to the competition between the MoS 2 -sapphire interface interaction and the MoS 2 -MoS 2 interlayer interaction, the thermal stability of monolayer MoS 2 on sapphire is superior to that of few-layer MoS 2 on sapphires.…”

“…93 The a -plane sapphire surface is composed of tightly packed atoms separated by grooves, with surface steps along the 〈11̄01〉 direction. 94 The structure along the step and perpendicular to the step are very different in the two directions, so the a -plane sapphire is dually symmetric, with reduced symmetry compared to the triple symmetric c -plane sapphire. Zhou et al used a water-assisted atmospheric pressure CVD method to grow WTe 2 nanosheets on c -plane and a -plane sapphire substrates.…”