Vienna University of Technology, Institute of Photonics , Gußhausstraße 27-29, 1040 Vienna, Austria.
Nano Lett. 2014 Nov 12;14(11):6165-70. doi: 10.1021/nl502339q. Epub 2014 Oct 13.
Atomically thin transition metal dichalcogenides have emerged as promising candidates for sensitive photodetection. Here, we report a photoconductivity study of biased mono- and bilayer molybdenum disulfide field-effect transistors. We identify photovoltaic and photoconductive effects, which both show strong photogain. The photovoltaic effect is described as a shift in transistor threshold voltage due to charge transfer from the channel to nearby molecules, including SiO2 surface-bound water. The photoconductive effect is attributed to the trapping of carriers in band tail states in the molybdenum disulfide itself. A simple model is presented that reproduces our experimental observations, such as the dependence on incident optical power and gate voltage. Our findings offer design and engineering strategies for atomically thin molybdenum disulfide photodetectors, and we anticipate that the results are generalizable to other transition metal dichalcogenides as well.
原子层厚的过渡金属二卤化物已成为灵敏光电探测的有前途的候选材料。在这里，我们报告了对偏置的单层和双层二硫化钼场效应晶体管的光电导研究。我们确定了光伏和光电导效应，这两种效应都表现出很强的光增益。光伏效应被描述为由于从沟道到附近分子（包括 SiO2 表面结合水）的电荷转移导致晶体管阈值电压的偏移。光电导效应归因于在二硫化钼本身的带尾态中载流子的俘获。提出了一个简单的模型，可以重现我们的实验观察结果，例如对入射光功率和栅极电压的依赖性。我们的发现为原子层厚的二硫化钼光电探测器提供了设计和工程策略，我们预计结果也可以推广到其他过渡金属二卤化物。
