Fully Dry Assembly of Graphene/MoS 2 van der Waals Heterojunctions for Self‐Powered Photodetection

Interfacial defects critically constrain carrier transport and charge separation in 2D van der Waals (vdW) heterojunction optoelectronic devices. Here, we report a graphene/MoS 2 vdW heterojunction photodetector fabricated via a fully dry, probe‐assisted assembly strategy implemented post‐electrode deposition. By avoiding polymer‐assisted transfer, wet chemical processing, and energetic post‐fabrication treatments, this approach minimizes interfacial contamination and preserves the structural integrity of the constituent layers. The resulting heterojunction exhibits pronounced diode‐like rectification with a rectification ratio of 3.2 × 10 4 and an on/off current ratio of 4.1 × 10 3 . At zero external bias, the device functions as a self‐powered photodetector with rise and fall times of 0.62 and 1.46 ms, respectively. At 532 nm and an incident optical power density of 11.32 mW/cm 2 , the device achieves a responsivity of 0.577 A/W and a specific detectivity of 7.2 × 10 10 Jones, with these figures of merit being comparable to those reported for state‐of‐the‐art self‐powered vdW heterojunction photodetectors. Temperature‐dependent measurements reveal that both electrical transport and photovoltaic responses are governed by thermally activated carrier injection and interfacial barrier modulation. This work establishes a low‐damage, deterministic approach for fabricating high‐quality vdW heterojunctions for high‐performance 2D optoelectronic devices.