Electrically Robust Single‐Crystalline WTe₂ Nanobelts for Nanoscale Electrical Interconnects

Abstract

As the elements of integrated circuits are downsized to the nanoscale, the current Cu‐based interconnects are facing limitations due to increased resistivity and decreased current‐carrying capacity because of scaling. Here, the bottom‐up synthesis of single‐crystalline WTe2 nanobelts and low‐ and high‐field electrical characterization of nanoscale interconnect test structures in various ambient conditions are reported. Unlike exfoliated flakes obtained by the top‐down approach, the bottom‐up growth mode of WTe2 nanobelts allows systemic characterization of the electrical properties of WTe2 single crystals as a function of channel dimensions. Using a 1D heat transport model and a power law, it is determined that the breakdown of WTe2 devices under vacuum and with AlOx capping layer follows an ideal pattern for Joule heating, far from edge scattering. High‐field electrical measurements and self‐heating modeling demonstrate that the WTe2 nanobelts have a breakdown current density approaching ≈100 MA cm−2, remarkably higher than those of conventional metals and other transition‐metal chalcogenides, and sustain the highest electrical power per channel length (≈16.4 W cm−1) among the interconnect candidates. The results suggest superior robustness of WTe2 against high‐bias sweep and its possible applicability in future nanoelectronics.

Synthesis of tungsten ditelluride thin films and highly crystalline nanobelts from pre-deposited reactants

“…This low resistivity is expected due to the semimetallic nature of WTe 2 . Interestingly, this resistivity matches almost exactly the values measured by Song et al [23] in their paper on the potential use of single-crystal WTe 2 nanobelts as electrical interconnects in nanoelectronics. Their synthesis method requires the deposition of films of W and Cu that are then exposed to Te vapour.…”

“…Works on thicker samples of WTe 2 generally show increasing resistivity as the temperature is increased. The magnitude of this effect is reported as being between ~ 5% and ~ 500% change over a similar temperature window to that examined in this work [23,31,51,75]. It is possible that effects such as the formation of a potential barrier at the contacts due to surface oxidation may also be influencing results seen in this and other works.…”

“…Some works on thin crystals of WTe 2 show a reduction in resistivity with increasing temperature due to Anderson localization effects. However, that was for much thinner (3-4 layer) flakes, while the nanobelt examined here was ~ 120 layers [15,23]. Works on thicker samples of WTe 2 generally show increasing resistivity as the temperature is increased.…”

“…Other works have examined WTe 2 for use in applications such as nanoscale electrical interconnects [23], electrocatalysis [24,25] and as an anode material for Na-ion batteries [26]. Additionally, WTe 2 has been touted as a promising candidate for large-gap quantum spin Hall insulators [5,21,22].…”

Fermi-level pinning-free WSe2 transistors via 2D van der Waals metal contacts and their complementary logic gate circuits

“…The Pd/Cl-SnSe2 junction exhibits a low contact resistance of ~0.164 kΩ μm at VGS = 0 V, which guarantees highly efficient carrier injection at the 3D metal/2D metal junction. Notably, this contact resistance value is lower than values obtained using a phase-engineered (0.2-0.3 kΩ µm), 23 3D metal/graphene (2-10 2 kΩ μm), 24,25 and 3D metal/2D 1T′-WTe2 contacts (0.4-1.03 kΩ μm), 26,27 which shows the great potential of our Cl-SnSe2 as a 2D metal contact. The inset in Fig.…”