Surface‐Shielding Nanostructures Derived from Self‐Assembled Block Copolymers Enable Reliable Plasma Doping for Few‐Layer Transition Metal Dichalcogenides

Precise modulation of electrical and optical properties of 2D transition metal dichalcogenides (TMDs) is required for their application to high‐performance devices. Although conventional plasma‐based doping methods have provided excellent controllability and reproducibility for bulk or relatively thick TMDs, the application of plasma doping for ultrathin few‐layer TMDs has been hindered by serious degradation of their properties. Herein, a reliable and universal doping route is reported for few‐layer TMDs by employing surface‐shielding nanostructures during a plasma‐doping process. It is shown that the surface‐protection oxidized polydimethylsiloxane nanostructures obtained from the sub‐20 nm self‐assembly of Si‐containing block copolymers can preserve the integrity of 2D TMDs and maintain high mobility while affording extensive control over the doping level. For example, the self‐assembled nanostructures form periodically arranged plasma‐blocking and plasma‐accepting nanoscale regions for realizing modulated plasma doping on few‐layer MoS₂, controlling the n‐doping level of few‐layer MoS₂ from 1.9 × 10¹¹ cm^?2 to 8.1 × 10¹¹ cm^?2 via the local generation of extra sulfur vacancies without compromising the carrier mobility.