Hoang Lauren, Jaikissoon Marc, Köroğlu Çağıl, Zhang Zhepeng, Bennett Robert K A, Song Jung-Hwan, Yang Jerry A, Ko Jung-Soo, Brongersma Mark L, Saraswat Krishna C, Pop Eric, Mannix Andrew J
Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States.
Department of Materials Science & Engineering, Stanford University, Stanford, California 94305, United States.
Nano Lett. 2024 Oct 4;24(41):12768-74. doi: 10.1021/acs.nanolett.4c02616.
Two-dimensional (2D) electronics require low contact resistance () to approach their fundamental limits. WS 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 conduction band. Here, we investigate the effects of contact size on nanoscale monolayer WS transistors and uncover that Ni contacts impart stress, which affects the WS device performance. The strain applied to the WS depends on contact size, where long (1 μm) contacts ( ≈ 1.7 kΩ·μm) show a 78% reduction in compared to shorter (0.1 μm) contacts ( ≈ 7.8 kΩ·μm). We also find that thermal annealing can relax the WS strain in long-contact devices, increasing 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.
二维（2D）电子器件需要低接触电阻（）才能接近其基本极限。WS是一种很有前景的二维半导体，常与镍接触电极配对，但考虑到镍的功函数与WS导带之间的非理想对准，它们的工作原理尚未得到很好的理解。在这里，我们研究了接触尺寸对纳米级单层WS晶体管的影响，并发现镍接触电极会施加应力，这会影响WS器件的性能。施加到WS上的应变取决于接触尺寸，长（1μm）接触电极（≈1.7kΩ·μm）与短（0.1μm）接触电极（≈7.8kΩ·μm）相比，接触电阻降低了78%。我们还发现，热退火可以缓解长接触器件中WS的应变，使接触电阻增加到8.5kΩ·μm。这些结果表明，热机械现象会显著影响二维半导体-金属接触，为通过纳米制造和热预算优化器件性能提供了机会。
