Gate-Tunable Photodiodes Based on Mixed-Dimensional Te/MoTe₂ Van der Waals Heterojunctions

The dangling-bond-free surfaces of 2D materials enable them to possess various degrees of freedom to form heterostructures with non-2D materials. This allows for the combination of the advantages of different dimensional materials to fabricate van der Waals (vdW) heterostructures, thereby improving device performance and even bringing diversity and novelty. Herein, a mixed-dimensional vdW heterostructure photodiode comprising a 1D tellurium (Te) nanowire and a 2D molybdenum ditelluride (MoTe₂) flake is demonstrated. Forward rectifying and backward rectifying characteristics are realized by applying different gate voltage. The device displays a broad spectral response from visible to near-infrared and exhibits ultrahigh external quantum efficiency of 7.16 × 10³% for photogating effect. Moreover, the response time can be improved by controlling gate voltage and a rapid response time of 4.8 ms is achieved. These mixed-dimensional vdW heterojunctions, which take advantages of both 1D and 2D semiconductors, will facilitate the development of next-generation electronics and optoelectronics.