A research team led by Prof. Young Hee LEE from the Institute for Basic Science successfully analyzed atomic structure and electrical characteristics of MoS2 which are labeled as new materials for the next generation, along with Graphene.

Grain boundaries in monolayer transition metal dichalcogenides have unique atomic defect structures and band dispersion relations that depend on the inter-domain misorientation angle. They explore misorientation angle-dependent electrical transport at grain boundaries in monolayer MoS2 by correlating the atomic defect structures of measured devices analysed with transmission electron microscopy, and first-principles calculations. Transmission electron microscopy indicates that grain boundaries are primarily composed of 5–7 dislocation cores with periodicity and additional complex defects formed at high angles, obeying the classical low-angle theory for angles o22_. The inter-domain mobility is minimized for angles o9_ and increases nonlinearly by two orders of magnitude before saturating atB16 cm2V_1 s_1 around misorientation angleE20_. This trend is explained via grain-boundary electrostatic barriers estimated from density functional calculations and experimental tunnelling barrier heights, which are E0.5 eV at low angles and E0.15 eV at high angles (≥20°).

The results provide practical expectations regarding transport properties in large-area films, which are restricted largely by the poor mobility across LA GBs. The results obtained in this work are applicable to other similar 2D systems, and contribute to the fundamental understanding of transport in semiconductors.

This work was published at Nature Communications, affiliated magazine with Nature. Please find published article as attached.