An image of this new device employing a multilayered WSe2 bulk flake is shown in Figure ("flake 2") and the dark current as well as the ON/OFF ratios are displayed in Figure . At zero bias and 2µW illumination at 635 nm, we find a photocurrent of more than 20 nA, hinting at the presence of a built-in electric field presumably either due to slight height differences of the flake within the channel or to altered electric contacting of the electrodes due to the electron beam evaporation process. Figure displays the non-steady state response and power spectrum of the new device (red curve) with a fall time < 2ns and a 3dB bandwidth of 230 MHz. For comparison, the previous device from Figure is also displayed (blue curve) to illustrate the effect of the reduced capacitance. In addition, we measure the power spectrum of a commercial photodiode with a nominal fall time of 200 ps (ochre curve) and expected 3dB bandwidth of 1.75 GHz to find essentially the same 230 MHz cut-off as with the improved WSe2 device. This strongly suggests that these measurements are set-up limited, presumably due to the applied cables, connectors, 600 MHz low pass filter and lock-in amplifier, and that the true speed of the improved WSe2 device might be even faster. Further evidence for such limitations is found in the periodic wiggles in the non-steady state response and the resulting noisy power spectrum, which can be attributed to reflections inside the cables as detailed in the SI, Fig. .