Direct Laser Writing of Au Top Contacts on WSe2 for High-Speed Photodetection

We demonstrate high-speed photodetectors based on bi-, few- and multilayered WSe2 flakes fabricated by high-resolution direct laser writing of Au top contacts from atomically precise gold nanoclusters as an alternative to conventional photolithography. Time-resolved steady-state and transient photoresponse measurements reveal remarkable switching speeds exhibiting response times down to 7 ns and electrical bandwidths up to 250 MHz. Key performance metrics, including responsivity, detectivity and external quantum yield are studied with respect to the applied irradiance and excitation wavelength. By demonstrating high-speed switching in thin-layered WSe2-based devices, this work highlights the potential of laser-written metal-semiconductor interfaces for high-speed optoelectronic applications of 2D materials.