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

Abstract

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.