Structural defects in a nanomesh of bulk MoS2 using an anodic aluminum oxide template for photoluminescence efficiency enhancement.

Two-dimensional (2D) materials beyond graphene have attracted considerable interest because of the zero bandgap drawbacks of graphene. Transition metal dichalcogenides (TMDs), such as MoS2 and WSe2, are the potential candidates for next 2D materials because atomically thin layers of TMDs exhibit unique and versatile electrical and optical properties. Although bulk TMDs materials have an indirect bandgap, an indirect-to-direct bandgap transition is observed in monolayers of TMDs (MoS2, WSe2, and MoSe2). Optical properties of TMD films can be improved by the introduction of structural defects. For example, large-area spatial tuning of the optical transition of bulk MoS2 films is achieved by using an anodic aluminum oxide (AAO) template to induce structural defects such as edge- and terrace-terminated defects in a nanomesh structure. Strong photoluminescence emission peaks with a band gap of 1.81 eV are observed, possibly because of radiative transition at the defect sites. This work shows that the AAO template lithography method has potential for the production of homogenous large-scale nanomesh structures for practical semiconductor processing applications in future MoS2-based electronic and optical devices.

Wafer-scale production of highly uniform two-dimensional MoS2 by metal-organic chemical vapor deposition.

Semiconducting two-dimensional (2D) materials, particularly extremely thin molybdenum disulfide (MoS2) films, are attracting considerable attention from academia and industry owing to their distinctive optical and electrical properties. Here, we present the direct growth of a MoS2 monolayer with unprecedented spatial and structural uniformity across an entire 8 inch SiO2/Si wafer. The influences of growth pressure, ambient gases (Ar, H2), and S/Mo molar flow ratio on the MoS2 layered growth were explored by considering the domain size, nucleation sites, morphology, and impurity incorporation. Monolayer MoS2-based field effect transistors achieve an electron mobility of 0.47 cm2 V-1 s-1 and on/off current ratio of 5.4 × 104. This work demonstrates the potential for reliable wafer-scale production of 2D MoS2 for practical applications in next-generation electronic and optical devices.