Direct Laser Writing of Au Top Contacts on WSe ₂ for High-Speed Photodetection

Photodetectors capable of GHz operation are essential for high-speed optical data transmission. However, practical implementation with TMDCs is severely limited by extrinsic factors. Standard photolithographic metallization introduces additional interfacial defects and parasitic effects, reducing the speed of the device. While contact printing represents a promising alternative approach to conventional photolithography, the lack of high-precision metal printing techniques has prevented the realization of printed high-speed optoelectronic applications. In this work, 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 metalloid gold nanoclusters. Time-resolved steady-state and transient photoresponse measurements reveal remarkable switching speeds, exhibiting response times down to 7 ns and electrical bandwidths of up to 250 MHz. Key performance metrics, including responsivity, detectivity, and external quantum efficiency, are investigated 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.