Controlled Synthesis of Ultrathin Cu2Te Nanosheets for High-Performance Photodetectors

Atomically thin 2D layered transition metal dichalcogenides (TMDs) have attracted widespread attention for their appealing electrical and optical properties and potential in constructing the next generation of highly integrated logic circuits. However, intrinsic 2D p-type semiconductor materials are still relatively scarce. Cu2Te, as a layered p-type material with a unique crystal structure, has rarely been reported for its electrical and photoelectric properties. Here, ultrathin single-crystalline Cu2Te nanosheets as thin as 2.6 nm on SiO2/Si and 1.6 nm on a 2D MoS2 substrate are directly realized by a modified spatially confined chemical vapor deposition (CVD) strategy. The thickness of the 2D Cu2Te nanosheets on SiO2/Si can be effectively controlled by adjusting the reaction temperature during synthesis. Importantly, the field-effect transistors based on the as-synthesized Cu2Te nanosheets show p-type transport behavior and have a high hole mobility of up to 184 cm2<middle dot>V-1<middle dot>s-1. The vertical Cu2Te/MoS2 heterojunction shows obvious current rectification behavior with a rectification ratio of about 600. Meanwhile, the Cu2Te photodetector exhibits an excellent photoresponsivity of 1.69 x 103 A<middle dot>W-1, an ultrahigh detectivity of 8.41 x 1015 Jones, and an external quantum efficiency of 4040%, superior to the many reported 2D-material-based photodetectors. Our work further enriches the library of CVD-grown p-type 2D materials and demonstrates their potential for electronic and optoelectronic applications.