Synthesis of Ultrathin 2D Nonlayered α-MnSe Nanosheets, MnSe/WS2 Heterojunction for High-Performance Photodetectors

Numerous efforts have been made to synthesize 2D atomic semiconductor materials and their heterojunctions because of the diverse novel properties and potential applications in constructing next-generation highly compact electronic and optoelectronic devices. However, intrinsic 2D p-type semiconductor materials are still scarce. Herein, to enrich the p-type 2D semiconductor family, epitaxial growth of a large-area, ultrathin 2D nonlayered p-type semiconductor alpha-MnSe on mica with the thickness down to one unit crystal cell (0.9 nm) is reported. Moreover, the thickness of the alpha-MnSe nanosheets can be systematically tailored from over 150 to 0.9 nm by increasing the flow rate of the carrier gas. X-ray-diffraction, transmission electron microscopy, and electron diffraction studies confirm that the resulting 2D nanosheets are high-quality single crystals. The photodetector based on the p-type alpha-MnSe nanosheet shows a fast response time of 4 ms. Furthermore, alpha-MnSe/WS2 heterojunctions are synthesized and a diode based on p-type alpha-MnSe and n-type WS2 displays outstanding photodetectivity (1.00 x 10(13) Jones), high photoresponsivity (49.1 A W-1), and an obvious rectification ratio (283). Together, the synthesis of alpha-MnSe and the alpha-MnSe/WS2 p-n heterojunction provides opportunities for next-generation electronics and optoelectronics.

Automated summary

This study reports the epitaxial growth of a large-area, ultrathin p-type 2D semiconductor material α-MnSe on mica, with the thickness down to 0.9 nm, which can be systematically controlled by adjusting the carrier gas flow rate. Photodetectors based on α-MnSe exhibit a fast response time of 4 ms, while diodes based on α-MnSe/WS2 heterojunctions show outstanding photodetectivity and high photoresponsivity.