Improved Self-Heating in Short-Channel Monolayer WS₂ Transistors with High-Thermal Conductivity BeO Dielectrics.

Abstract

Two-dimensional semiconducting transition metal dichalcogenides (TMDs) enable ultimate channel length scaling of transistor technology due to their atomic-thin body nature, which also brings the challenge of a pronounced self-heating effect inside the ultrathin channel. In particular, high current density under high electric field could lead to negative differential resistance behavior due to self-heating, not only limiting the current carrying capability of the TMDs transistors but also leading to severe reliability issues. Here, we report high-performance monolayer WS₂ transistors on a high-thermal-conductivity BeO dielectric with effective suppression of the self-heating effects, eliminating the negative differential resistance behavior at high field, as observed in the case of the HfO₂ dielectric. The monolayer CVD WS₂ device on BeO with a 50 nm channel length exhibits a record-high on-state current of 325 μA/μm, transconductance (<i>g</i>_m) of 150 μS/μm, and a on/off ratio of 1.8 × 10⁸ at <i>V</i>_ds = 1 V, far exceeding previous results.