Nanoscale patterning on layered MoS₂ with stacking-dependent morphologies and optical tunning for phototransistor applications

Nanoscale patterning has attracted considerable interest as a novel engineering technology for two-dimensional (2D) nanomaterials for various applications such as electronics, sensors, and catalysts. However, research on nanopatterning technologies that reflect the unique structural and electrical characteristics of 2D nanomaterials remains insufficient. In this study, we present a nanoscale patterning of two different polygons on layered molybdenum disulfide (MoS₂), where the nanostructures are controlled by the stacking structure of MoS₂. We investigate the dependence of nanopore edge stability on the stacking structure of MoS₂ using density functional theory calculations and find the different geometric effects of the two nanopatterns on the band-structure modulation of semiconducting MoS₂. Consistent with the theoretical calculations, we fabricate nanoporous MoS₂ with hexagonal nanopores for AA’ and triangular nanopores for AB stacked MoS₂ films. The AA’ MoS₂ has narrow nanoribbons between the two hexagonal nanopores, resulting in a lateral quantum confinement effect, whereas the edge exposure effect is more dominant for the bandgap increase in the triangular nanoporous structure. Nanopatterns contribute to generating in-gap state of MoS₂, significantly enhancing the photoelectrical characteristics of MoS₂ phototransistors. Especially, the photogating effect is higher for AA’ MoS₂ phototransistors with hexagonal nanoholes than AB MoS₂ with triangular nanoholes. This study provides new insights into nanoscale patterning and band structure engineering of layered 2D materials for various optoelectrical applications.