Chemically Tuned p‐ and n‐Type WSe 2 Monolayers with High Carrier Mobility for Advanced Electronics

Monolayers of transition metal dichalcogenides (TMDCs) have attracted a great interest for post‐silicon electronics and photonics due to their high carrier mobility, tunable bandgap, and atom‐thick 2D structure. With the analogy to conventional silicon electronics, establishing a method to convert TMDC to p‐ and n‐type semiconductors is essential for various device applications, such as complementary metal‐oxide‐semiconductor (CMOS) circuits and photovoltaics. Here, a successful control of the electrical polarity of monolayer WSe 2 is demonstrated by chemical doping. Two different molecules, 4‐nitrobenzenediazonium tetrafluoroborate and diethylenetriamine, are utilized to convert ambipolar WSe 2 field‐effect transistors (FETs) to p‐ and n‐type, respectively. Moreover, the chemically doped WSe 2 show increased effective carrier mobilities of 82 and 25 cm 2 V −1 s −1 for holes and electrons, respectively, which are much higher than those of the pristine WSe 2 . The doping effects are studied by photoluminescence, Raman, X‐ray photoelectron spectroscopy, and density functional theory. Chemically tuned WSe 2 FETs are integrated into CMOS inverters, exhibiting extremely low power consumption ( ≈ 0.17 nW). Furthermore, a p‐n junction within single WSe 2 grain is realized via spatially controlled chemical doping. The chemical doping method for controlling the transport properties of WSe 2 will contribute to the development of TMDC‐based advanced electronics.