High-performing van der Waals heterostructure photodetectors using CuInP₂S₆-based ferroelectric gate

Two-dimensional (2D) ferroelectric materials, which own the stable layered structures and reduced surface energy, have recently attracted great attentions. So far, multiple have exploited these emerging ferroelectric materials to demonstrate atomically-thin and multi-functional electronic devices, such as memory and logical devices. But their potential applications on optoelectronics remain largely unexplored. Here, we demonstrate a new type of van der Waal heterostructure photodetector that includes a monolayer graphene channel and a CuInP₂S₆-based ferroelectric gate. By exploiting this ferroelectric gate, we show our developed detector, operated within the visible range, can exhibit ultrahigh photoresponsivity approaching 10⁵ A/W as well as fast operation speed (~MHz bandwidth). In addition, our characterization indicates that its noise equivalent power can be as low as ~tens pW/Hz^1/2 at room temperature operation. Such results indicate our developed detector can be useful to diverse sensing or spectroscopic applications.