Engineering 2D Van der Waals Electrode via MBE Grown Weyl Semimetal 1T-WTe2 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-WTe2 has attracted attention for its excellent electrical transport, quantum phenomena, and Weyl semimetallic properties. Here, we demonstrate the direct wafer-scale growth of 1T-WTe2 via molecular beam epitaxy (MBE) and its use as a 2D contact for layered materials such as InSe. The 1T WTe2/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 WTe2 photodetectors show broad photoresponsivity (0.14 to 217.58 A/W) under NIR to DUV illumination with fast rise/fall times of 42/126 ms, compared to lower responsivity (0.000865 A/W to 3.64 A/W) and slower response (150/144 ms) for InSe/Ti Au devices. The 1T WTe2/InSe devices thus exhibit approximately 60 times higher responsivity and 4 times faster response than conventional metal contacts. These results establish MBE-grown 1T-WTe2 as an effective 2D electrode, enhancing photodetection performance while simplifying device architecture, making it a strong candidate for next generation nanoelectronic and optoelectronic devices.