High-Performance Single Layered WSe2 p-FETs with Chemically Doped Contacts

We report high performance p-type field-effect transistors based on single layered (thickness, similar to 0.7 nm) WSe2 as the active channel with chemically doped source/drain contacts and high-K gate dielectrics. The top-gated monolayer transistors exhibit a high effective hole mobility of -ISO cm(2)/(V s), perfect subthreshold swing of similar to 60 mV/dec, and I-ON/'OFF of >10(6) at room temperature. Special attention is given to lowering the contact resistance for hole injection by using high work function Pd contacts along with degenerate surface doping of the contacts by patterned NO2 chemisorption on WSe2. The results here present a promising material system and device architecture for p-type monolayer transistors with excellent characteristics.