Chromatic tuning of exciton state in MoS2 monolayer via tailoring Moiré correlation with a sapphire substrate

Abstract This study attempts to elucidate the specific Moiré correlation and associated exciton properties within MoS2 monolayers randomly orientated grown on a c-cut single-crystalline sapphire substrate, facilitating a distinct Moiré correlation. Notably, the energy of the exciton state in MoS2 monolayers appears periodically linked to the stacking geometry with the sapphire substrate. Specifically, coherent stacking as observed in MoS2[110]/sapphire[110] configurations results in heightened exciton energy, while 30-degree-misaligned stacking such as MoS2[110]/sapphire[010] yields lower exciton energy. The variation in exciton energy, consequent to alterations in the stacking geometry between MoS2 and sapphire, thus exhibits a 6-fold periodicity, reflective of the hexagonal nature of both MoS2 and sapphire. Furthermore, the exciton state originating from the 30-degree-misaligned correlation emerges as an electronic destination upon aging MoS2 monolayers on sapphire, leading to a cessation of the 6-fold periodicity and a subsequent decline in exciton energy. This study underscores the potential for manipulating the crystallographic stacking between single-crystalline MoS2 monolayers and sapphire substrates to serve as a versatile platform for investigating photonics in the MoS2-based heterostructures.