@article{Zhang2023, 
author = {Lei Zhang and Zeya Li and Ying Deng and Li Li and Zhansheng Gao and Jiabiao Chen and Zhengyang Zhou and Junwei Huang and Weigao Xu and Xuewen Fu and Hongtao Yuan and Feng Luo and Jinxiong Wu},
title = {Temperature-driven reversible structural transformation and conductivity switching in ultrathin Cu9S5 crystals},
year = {2023},
journal = {Nano Research},
volume = {16},
number = {7},
pages = {10515-10521},
keywords = {chemical vapor deposition, reversible phase transition, ultrathin Cu9S5 crystals, ultrahigh carrier density, conductivity switching},
url = {https://www.sciopen.com/article/10.1007/s12274-023-5805-9},
doi = {10.1007/s12274-023-5805-9},
abstract = {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 Cu9S5 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 Cu9S5 (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 hexagonal β phase and low-temperature β’ phase with a superstructure. Our work provides new insights to understand the physical properties of ultrathin Cu9S5 crystals, and brings new blood to the 2D materials family with reversible phase transitions.}
}