Fig. 1. (Color online) Schematic diagram of ReSe₂/WSe₂ photodetector. (a) Optical microscopy image of a ReSe₂/WSe₂ vdWH device. (b) Schematic diagram of the ReSe₂/WSe₂ vdWH device. (c) Raman spectra of the WSe₂, ReSe₂, and ReSe₂/WSe₂ vdWH. (d) Thickness of individual ReSe₂ and WSe₂ layers.

Fig. 2. (Color online) Electrical and photoelectric properties of ReSe₂/WSe₂ vdWH FET. (a) Transfer characteristic curves of the individual ReSe₂ FET (the inset is the WSe₂ FET). (b) I_ds–V_ds curves of ReSe₂/WSe₂ vdWH FET under the increasing gate voltage from –10 to 40 V. (c) I_ds–V_ds curves of ReSe₂/WSe₂ photodetector under illumination of 520 nm laser. (d) Energy band diagrams of devices in dark and under illumination.

Fig. 3. (Color online) Performence characterization of ReSe₂/WSe₂ vdWH photodetector. (a) Responsivity and detectivity as a function of incident power. (b) Output electrical power P_el versus V_ds. (c) SPCM images of the device. (d) Time-resolved photoresponse of the device.

Fig. 4. (Color online) Polarized properties of ReSe₂/WSe₂ device. (a) SPCM images of device under 520 nm light with different polarization directions (marked by orange arrows). (b) Corresponding photocurrent as a function of polarization angle.