A simple 230 MHz photodetector based on exfoliated WSe₂ multilayers

We demonstrate 230 MHz photodetection and a switching energy of merely 27 fJ using WSe₂ multilayers and a very simple device architecture. This improvement over previous, slower WSe₂ devices is enabled by systematically reducing the RC constant of devices through decreasing the photoresistance and capacitance. In contrast to MoS₂, reducing the WSe₂ thickness toward a monolayer only weakly decreases the response time, highlighting that ultrafast photodetection is also possible with atomically thin WSe₂. Our work provides new insights into the temporal limits of pure transition metal dichalcogenide photodetectors and suggests that gigahertz photodetection with these materials should be feasible.