摘要
Two-dimensional(2D)materials with reversible phase transformation are appealing for their rich physics and potential applications in information storage.However,up to now,reversible phase transitions in 2D materials that can be driven by facile nondestructive methods,such as temperature,are still rare.Here,we introduce ultrathin Cu_(9)S_(5)crystals grown by chemical vapor deposition(CVD)as an exemplary case.For the first time,their basic electrical properties were investigated based on Hall measurements,showing a record high hole carrier density of~1022 cm^(-3) among 2D semiconductors.Besides,an unusual and repeatable conductivity switching behavior at~250 K were readily observed in a wide thickness range of CVD-grown Cu_(9)S_(5)(down to 2 unit-cells).Confirmed by in-situ selected area electron diffraction,this unusual behavior can be ascribed to the reversible structural phase transition between the room-temperature hexagonalβphase and low-temperatureβ’phase with a superstructure.Our work provides new insights to understand the physical properties of ultrathin Cu_(9)S_(5)crystals,and brings new blood to the 2D materials family with reversible phase transitions.
基金
J.X.W.acknowledges financial support from the National Natural Science Foundation of China(NSFC)(No.92064005)
Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure(No.SKL202211SIC)
H.T.Y.acknowledges the support from the NSFC(Nos.51861145201,52072168,and 21733001)
the National Key Research and Development Program of China(No.2018YFA0306200)
J.W.H.acknowledges the support from the National Key Research and Development Program of China(No.2021YFA1202901)
X.W.F.acknowledges financial support from the NSFC at grant(Nos.11974191 and 2217830)
the National Key Research and Development Program of China at grant(No.2020YFA0309300)
the Natural Science Foundation of Tianjin at grant(Nos.20JCZDJC00560 and 20JCJQJC00210)
the 111 Project(No.B23045).
