Synthesis and Optoelectronic Applications of a Stable Type 2D Material: α-MnS.

α-MnS, as a nonlayered type material with a wide band gap of 2.7 eV, has been expected to supplement the scarcity of two-dimensional (2D) type semiconductors, which are desperately required for constructing atomically thin junctions. However, the preparation and property investigation of 2D α-MnS has scarcely been reported so far. Herein, we report the controlled synthesis of ultrathin large-scale α-MnS single crystals down to 4.78 nm a facile chemical vapor deposition (CVD) method. Importantly, top-gating field-effect transistors based on the as-synthesized α-MnS nanosheets show type transport behavior with an ultrahigh on/off ratio exceeding 10, surpassing most reported type 2D materials. Meanwhile, α-MnS phototransistors exhibit an ultrahigh detectivity of 3.2 × 10 Jones, as well as an excellent photoresponsivity of 139 A/W and a fast response time of 12 ms. Besides, outstanding environmental stability and admirable flexibility have also been demonstrated in the as-synthesized α-MnS nanosheets. We believe that this work broadens the scope of the CVD synthesis strategy for various type 2D materials and demonstrates their significant application potentials in electronics and optoelectronics.