50 MHz WSe2 Photodetectors from Roll-to-Roll Exfoliated Films.

We investigate the time-resolved photodetection characteristics of multilayer WSe2 films fabricated via roll-to-roll mechanical exfoliation. By systematically studying the bias and irradiance dependence of the photocurrent dynamics, and by employing spatially resolved photocurrent mapping, we provide insights into the mechanisms governing the device response. We demonstrate a pronounced irradiance dependence of the response times and reveal decay times of 9.8 ns as well as 3 dB electrical bandwidths exceeding 50 MHz, rendering these devices on par with high-quality, manually exfoliated WSe2 photodetectors. These results establish roll-to-roll exfoliation as a powerful and scalable fabrication technique capable of producing high-speed photodetectors.