High-performance p-type bilayer WSe₂ field effect transistors by nitric oxide doping

Two-dimensional (2D) materials are promising candidates for next-generation electronics, but the realization of high-performance p-type 2D field-effect transistors (FETs) has remained challenging, hindering the development of fully integrated 2D complementary metal-oxide-semiconductor (CMOS) technology. Here, we present p-type 2D FETs based on bilayer WSe₂ synthesized via an industry-compatible metal-organic chemical vapor deposition (MOCVD) process. These devices achieve on-state current as high as 421 μA/μm at a drain voltage of 1 V and a gate overdrive voltage of 2.5 V, an on/off current ratio exceeding 10⁷, and a subthreshold swing as low as 75 mV/decade. Key device parameters include a contact resistance down to 1.3 kΩ-µm, a field-effect hole mobility of 16.1 cm²V^-1s^-1, and a peak transconductance of 250 µS/µm. This high performance is enabled by p-type doping through nitric oxide (NO) treatment at 100 °C for 30 minutes. Furthermore, we scaled the channel length down to 50 nm, integrated a high-κ gate dielectric with an equivalent oxide thickness of ~2.3 nm, and analyzed over 300 devices. We also investigated the temporal and thermal stability of p-type doping, providing insights into the underlying NO doping mechanism. Our findings help to address a long-standing challenge in 2D materials research and offer a promising solution to realize high-performance p-type 2D FETs for future CMOS applications.