Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.
Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, Singapore, 138634, Republic of Singapore.
Adv Mater. 2017 Dec;29(46). doi: 10.1002/adma.201702917. Epub 2017 Oct 17.
A demonstration is presented of how significant improvements in all-2D photodetectors can be achieved by exploiting the type-II band alignment of vertically stacked WS /MoS semiconducting heterobilayers and finite density of states of graphene electrodes. The photoresponsivity of WS /MoS heterobilayer devices is increased by more than an order of magnitude compared to homobilayer devices and two orders of magnitude compared to monolayer devices of WS and MoS , reaching 10 A W under an illumination power density of 1.7 × 10 mW cm . The massive improvement in performance is due to the strong Coulomb interaction between WS and MoS layers. The efficient charge transfer at the WS /MoS heterointerface and long trapping time of photogenerated charges contribute to the observed large photoconductive gain of ≈3 × 10 . Laterally spaced graphene electrodes with vertically stacked 2D van der Waals heterostructures are employed for making high-performing ultrathin photodetectors.
本文展示了如何通过利用垂直堆叠的 WS / MoS 半导体异质结的 II 型能带排列和石墨烯电极的有限态密度，显著提高全 2D 光电探测器的性能。与同质结器件相比，WS / MoS 异质结器件的光电响应率提高了一个数量级以上，与 WS 和 MoS 的单层器件相比提高了两个数量级，在 1.7 × 10 mW cm 的光照功率密度下达到 10 A W。性能的大幅提高归因于 WS 和 MoS 层之间的强库仑相互作用。WS / MoS 异质界面处的有效电荷转移和光生载流子的长俘获时间有助于观察到的大光电导增益 ≈3 × 10 。采用具有垂直堆叠二维范德华异质结构的横向间隔的石墨烯电极，用于制造高性能超薄光电探测器。
