Tungsten Oxide Adhesion Layer for Low Resistance Hole Contacts to WSe 2

The dangling-bond-free surfaces of transition metal dichalcogenides (TMDs) fundamentally challenge the creation of strongly bonded metal contacts. Commonly used interfacial adhesion layers, such as titanium, have unfavorable band alignment to the valence band of TMDs. Here, we introduce tungsten oxide (WOx) as an interfacial adhesion layer for low resistance hole contacts on monolayer WSe2. We show that the WOx adhesion layer exhibits a 2-fold increase in adhesion force on both WSe2 and SiO2 surfaces compared to the conventional titanium adhesion layer while enabling a low hole contact resistance of Rc = 0.2 kΩ·μm on monolayer WSe2. This work provides a method to facilitate a robust and reliable way to create highly adhesive contacts on atomically smooth TMD surfaces that are suitable for large-scale integration.