  Two-dimensional molybdenum disulfide (MoS$_2$) featuring atomically thin
thickness and unique electronic structure with favorable bandgap has been
widely recognized as an attractive new material for the development of the next
generation of ultra-compact, light-weight optoelectronic components. In
parallel, the recently emerged metasurfaces have demonstrated exceptional
controllability over electromagnetic field within ultra-compact subwavelength
dimension offering an unprecedented approach to improve the performance of
optoelectronic devices. In this work, we are proposing an integration of
metasurfaces with 2D semiconductor materials to achieve polarization sensitive,
fast-response photodetectors. The reported devices are among the most compact
hybrid MoS2-gap-plasmon metasurface detectors. Relying on the significant
electromagnetic field confinement provided by the metasurfaces to enhance light
absorption and to reduce the surface states, which generally limit the
photo-generated carriers lifetime, we measured enhanced photocurrent and a fast
detection speed. Moreover, the strong optical anisotropy introduced by the
metasurfaces is used to efficiently control the polarization sensitivity of the
photodetector. This work provides a feasible and effective solution to improve
the performance of two-dimensional materials based photodetectors.
