State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of SciencesP.O. Box 912, Beijing 100083, China.
Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.
Sci Rep. 2014 Jun 9;4:5209. doi: 10.1038/srep05209.
The photoelectrical properties of multilayer WS₂ nanoflakes including field-effect, photosensitive and gas sensing are comprehensively and systematically studied. The transistors perform an n-type behavior with electron mobility of 12 cm(2)/Vs and exhibit high photosensitive characteristics with response time (τ) of <20 ms, photo-responsivity (Rλ) of 5.7 A/W and external quantum efficiency (EQE) of 1118%. In addition, charge transfer can appear between the multilayer WS₂ nanoflakes and the physical-adsorbed gas molecules, greatly influencing the photoelectrical properties of our devices. The ethanol and NH₃ molecules can serve as electron donors to enhance the Rλ and EQE significantly. Under the NH3 atmosphere, the maximum Rλ and EQE can even reach 884 A/W and 1.7 × 10(5)%, respectively. This work demonstrates that multilayer WS₂ nanoflakes possess important potential for applications in field-effect transistors, highly sensitive photodetectors, and gas sensors, and it will open new way to develop two-dimensional (2D) WS₂-based optoelectronics.
我们综合系统地研究了多层 WS₂ 纳米片的光电性能，包括场效应、光敏和气体传感。晶体管表现出 n 型行为，电子迁移率为 12 cm²/Vs，并表现出高灵敏度的光敏特性，响应时间（τ）<20 ms，光响应率（Rλ）为 5.7 A/W，外量子效率（EQE）为 1118%。此外，多层 WS₂ 纳米片与物理吸附气体分子之间可以发生电荷转移，这极大地影响了我们器件的光电性能。乙醇和 NH₃ 分子可以作为电子供体，显著增强 Rλ 和 EQE。在 NH₃ 气氛下，最大的 Rλ 和 EQE 甚至可以分别达到 884 A/W 和 1.7×10(5) %。这项工作表明，多层 WS₂ 纳米片在场效应晶体管、高灵敏度光电探测器和气体传感器方面具有重要的应用潜力，为开发基于二维（2D）WS₂ 的光电技术开辟了新途径。
