  Two-dimensional (2D) semimetals beyond graphene have been relatively
unexplored in the atomically-thin limit. Here we introduce a facile growth
mechanism for semimetallic WTe2 crystals, then fabricate few-layer test
structures while carefully avoiding degradation from exposure to air. Low-field
electrical measurements of 80 nm to 2 um long devices allow us to separate
intrinsic and contact resistance, revealing metallic response in the thinnest
encapsulated and stable WTe2 devices studied to date (3 to 20 layers thick).
High-field electrical measurements and electro-thermal modeling demonstrate
that ultra-thin WTe2 can carry remarkably high current density (approaching 50
MA/cm2, higher than most common interconnect metals) despite a very low thermal
conductivity (of the order ~3 W/m/K). These results suggest several pathways
for air-stable technological viability of this layered semimetal.
