Coherent Atomic and Electronic Heterostructures of Single-Layer MoS₂

TLDR

Nanoscale heterostructures such as quantum dots, nanowires, and nanosheets enable advanced electronic and photonic devices, and coherent, passivated interfaces between electronically dissimilar materials are typically achieved through composition or doping modulation or lattice‑matched heteroepitaxy. Chemically exfoliated MoS₂ single layers form lattice‑matched, chemically homogeneous atomic and electronic heterostructures comprising coexisting metallic and semiconducting polymorphs, as revealed by high‑resolution STEM, indicating promise for molecular‑scale electronic devices in atomically thin 2D layers.

Abstract

Nanoscale heterostructures with quantum dots, nanowires, and nanosheets have opened up new routes toward advanced functionalities and implementation of novel electronic and photonic devices in reduced dimensions. Coherent and passivated heterointerfaces between electronically dissimilar materials can be typically achieved through composition or doping modulation as in GaAs/AlGaAs and Si/NiSi or heteroepitaxy of lattice matched but chemically distinct compounds. Here we report that single layers of chemically exfoliated MoS2 consist of electronically dissimilar polymorphs that are lattice matched such that they form chemically homogeneous atomic and electronic heterostructures. High resolution scanning transmission electron microscope (STEM) imaging reveals the coexistence of metallic and semiconducting phases within the chemically homogeneous two-dimensional (2D) MoS2 nanosheets. These results suggest potential for exploiting molecular scale electronic device designs in atomically thin 2D layers.