Understanding the Impact of Contact-Induced Strain on the Electrical Performance of Monolayer WS<sub>2</sub> Transistors.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39365938.
- Also identified by DOI 10.1021/acs.nanolett.4c02616 and PMC identifier 11488502.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Two-dimensional (2D) electronics require low contact resistance (<i>R</i><sub>C</sub>) to approach their fundamental limits. WS<sub>2</sub> is a promising 2D semiconductor that is often paired with Ni contacts, but their operation is not well understood considering the nonideal alignment between the Ni work function and the WS<sub>2</sub> conduction band. Here, we investigate the effects of contact size on nanoscale monolayer WS<sub>2</sub> transistors and uncover that Ni contacts impart stress, which affects the WS<sub>2</sub> device performance. The strain applied to the WS<sub>2</sub> depends on contact size, where long (1 μm) contacts (<i>R</i><sub>C</sub> ≈ 1.7 kΩ·μm) show a 78% reduction in <i>R</i><sub>C</sub> compared to shorter (0.1 μm) contacts (<i>R</i><sub>C</sub> ≈ 7.8 kΩ·μm). We also find that thermal annealing can relax the WS<sub>2</sub> strain in long-contact devices, increasing <i>R</i><sub>C</sub> to 8.5 kΩ·μm. These results reveal that thermo-mechanical phenomena can significantly influence 2D semiconductor-metal contacts, presenting opportunities to optimize device performance through nanofabrication and thermal budget.