Gate-driven band modulation hyperdoping for high-performance p-type 2D semiconductor transistors.

Tailoring carrier density in atomically thin two-dimensional (2D) semiconductors is challenging because of the inherently limited physical space for incorporating charge dopants. Here, we report that interlayer charge-transfer doping in type III van der Waals heterostructures can be greatly modulated by an external gate to realize a hyperdoping effect. Systematic gated-Hall measurements revealed that the modulated carrier density is about five times that of the gate capacitive charge, achieving an ultrahigh 2D hole density of 1.49 × 1014 per square centimeter, far exceeding the maximum possible electrostatic doping limit imposed by typical dielectric breakdown. The highly efficient hole-doping enables high-performance p-type 2D transistors with an ultralow contact resistance of ~0.041 kilohm micrometers and a record-high ON-state current density of ~2.30 milliamperes per micrometer. Editor's summary: Band alignment effects enable high levels of hole doping in a tungsten diselenide bilayer through its transfer of electrons into an adjacent tin disulfide monolayer. Ion implantation is often used to dope in semiconductor films, but this is difficult in few-layer transition metal dichalcogenides. Zhao et al. show that tuning of the band offset and charge transfer across the van der Waals interface with an external gate bias can produce a hole density of 1.49 × 1014 per square centimeter, which is about five times the conventional dielectric limit. —Phil Szuromi [ABSTRACT FROM AUTHOR]