Non-planar vertical photodetectors based on free standing two-dimensional SnS nanosheets.

The development trend of modern electronics and optoelectronics is towards continuous high integration and miniaturization. Using vertical configurations with three-dimensional geometry, it is easy to establish a higher integration density than the traditional planar one, and thus, this technology shows great promise for designing the next-generation electronics/optoelectronic devices. Two-dimensional (2D) layered metal dichalcogenides (2D-LMDs) are important building blocks for electronic/optoelectronic devices, where they are usually grown in parallel to the substrates during chemical vapor deposition (CVD), and consequently they are solely exploited to fabricate lateral structure devices with planar geometry. In this research, for the first time the vertical growth of free standing 2D layered nanosheets of hexagonal tin disulfide (SnS) on a flat substrate was realized using a modified CVD method. Furthermore, it was successfully demonstrated, at the first attempt, that a type of non-planar vertical photodetector could be fabricated using free standing SnS nanosheets and this detector showed promise for photodetection applications. This work prepares the way for the growth of monodisperse vertical 2D-LMD nanosheets on flat substrates, and expands their use from conventional lateral structure devices to non-planar vertical electronic/optoelectronic devices.