High-performance van der Waals stacked transistors based on ultrathin GaPS dielectrics.

Exploring high-κ gate dielectrics is crucial for the achievement of high-performance field-effect transistors (FETs). Here, we report the synthesis of a few-layer wide bandgap semiconductor gallium thiophosphate (GaPS), which can be easily mechanically exfoliated from a bulk material. The few-layered GaPS flakes exhibit a relative dielectric constant of approximately 5.3. Two-dimensional (2D) van der Waals heterostructure FETs utilizing atomically smooth GaPS flakes as the top-gate dielectric layer and MoS as the channel material were fabricated, showing a high on-off ratio exceeding 10 with a subthreshold swing as low as 80 mV per decade. Our findings indicate that few-layer GaPS is a high-performance dielectric candidate for two-dimensional transistors, which enrich the high-κ 2D community and pave the way for fabricating modern electronic devices.