Engineering 2D Van der Waals Electrode via MBE‐Grown Weyl Semimetal 1T′‐WTe 2 for Enhanced Photodetection in InSe

Abstract Achieving low contact resistance in advanced quantum electronic devices remains a critical challenge. With the growing demand for faster and energy‐efficient devices, 2D contact engineering offers a promising solution. Beyond graphene, 1T′‐WTe 2 has attracted attention for its excellent electrical transport, quantum phenomena, and Weyl semimetallic properties. Here, the direct wafer‐scale growth of 1T′‐WTe 2 via molecular beam epitaxy (MBE) and its use as a 2D contact for layered materials, such as InSe, are demonstrated. The 1T′‐WTe 2 /InSe interface exhibits a barrier height nearly half that of conventional metal contacts, and its contact resistance is reduced by a factor of 21, effectively suppressing Fermi‐level pinning and enabling efficient electron injection. InSe/1T′‐WTe 2 photodetectors show broad photoresponsivity (0.14–217.58 A W −1 ) under NIR to DUV illumination with fast rise/fall times of 42/126 ms, compared to lower responsivity (8.65 × 10 −4 –3.64 A W −1 ) and slower response (150/144 ms) for InSe/Ti–Au devices. The 1T′‐WTe 2 /InSe devices thus exhibit ≈60 × higher responsivity and ≈4 × faster response than conventional metal contacts. These results establish MBE‐grown 1T′‐WTe 2 as an effective 2D electrode, enhancing photodetection performance while simplifying device architecture, making it a strong candidate for next‐generation nanoelectronic and optoelectronic devices.