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

Abstract

We report high performance p-type field-effect transistors based on single layered (thickness, ∼0.7 nm) WSe₂ as the active channel with chemically doped source/drain contacts and high-κ gate dielectrics. The top-gated monolayer transistors exhibit a high effective hole mobility of ∼250 cm²/(V s), perfect subthreshold swing of ∼60 mV/dec, and I_ON/I_OFF of >10⁶ 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.