Wafer-scale CVD Monolayer WSe2 p-FETs with Record-high 727 μA/μm Ion and 490 μS/ μm gmax via Hybrid Charge Transfer and Molecular Doping

This study introduces a novel hybrid p-doping strategy, integrating tungsten oxide (WO
x
) charge transfer and nitric oxide (NO) molecular doping with wafer-scale CVD grown monolayer tungsten diselenide (1L-WSe
2
). This hybrid doping approach has enabled a record-high on-current I
ON
of 727 μA/μm at a V
DS
of -1.5 V and a record-high transconductance (g
m
) of 490 μS/μm, while maintaining an excellent on-off current ratio of ~ 9 orders of magnitude in wafer-scale CVD 1L-WSe
2
p-FETs. We fabricated field-effect transistors in which 1L-WSe
2
is encapsulated by its native oxide WO
x
interfacial layer (IL). Analogous to the role of SiO
2
IL in Si CMOS, the native oxide WO
x
IL can effectively preserve intrinsic channel properties and allow for threshold voltage (V
TH
) tuning without compromising the on-off ratio. Furthermore, nitric oxide (NO) molecular doping was employed to further shift V
TH
for p-type doping. Unlike most reported doping techniques, NO doping improves the device on-current as well as the subthreshold swing (SS), without sacrificing the on-off ratio. This pioneering hybrid doping scheme could lay the foundation for the development of high-performance PMOS devices based on 2D WSe
2
.