Nanoscale strain engineering
Metallic contacts are a critical component of most 2D devices, and contact resistance has remained a persistent challenge that limits the performance of nanoscale devices. Optimizing contacts has thus become a high priority in 2D materials research.
In our recent work, we identified nanoscale strain gradients as a significant factor in reducing contact resistance in WS₂ transistors.
Although nickel (Ni) is widely employed as a good contact material for n-type WS₂, its workfunction alignment is suboptimal. Our study focused on how geometry-dependent strain, imparted by Ni thin-film electrodes, influences contact resistance.
We discovered that strain-inducing long contacts (1 µm wide) exhibit approximately twice the on-state current density of shorter contacts (0.1 µm wide) due to strain effects. These findings highlight the often-overlooked role of contact-induced strain, which can be as impactful as workfunction alignment in determining contact performance. This suggests new directions for contact optimization and underscores the importance of quantifying strain in future studies on 2D material contact resistance.
We plan to leverage these capabilities in future nanoscale electronic and optoelectronic devices.