Graphene/MoS 2 /Si Nanowires Schottky-NP Bipolar van der Waals Heterojunction for Ultrafast Photodetectors

Here, we demonstrate a novel 2-D–3-D graphene (Gr)/MoS 2 /Si nanowires Schottky-NP bipolar van der Waals heterostructure, which allows the combination of the unique properties of 2-D layered materials with the proven merits of well-developed silicon technologies. Significantly, the resultant devices exhibit an ultrahigh response speed of 17 ns with a broad spectral response characteristic, which represents most fast response for 2-D transition metal dichalcogenide (TMD)-based photodetectors and is comparable to that of commercial Si photodetectors. A high responsivity of 0.6 A $\text{W}^{-{1}}$ and a detectivity of ${8}\times {10}^{{12}}$ Jones are also achieved. This result suggests a pathway for the fabrication of high-speed photodetectors based on TMDs.