Yin Jianbo, Wang Huan, Peng Han, Tan Zhenjun, Liao Lei, Lin Li, Sun Xiao, Koh Ai Leen, Chen Yulin, Peng Hailin, Liu Zhongfan
Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, 202 Chengfu Road, Haidian District, Beijing 100871, China.
Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
Nat Commun. 2016 Mar 7;7:10699. doi: 10.1038/ncomms10699.
Graphene with ultra-high carrier mobility and ultra-short photoresponse time has shown remarkable potential in ultrafast photodetection. However, the broad and weak optical absorption (∼ 2.3%) of monolayer graphene hinders its practical application in photodetectors with high responsivity and selectivity. Here we demonstrate that twisted bilayer graphene, a stack of two graphene monolayers with an interlayer twist angle, exhibits a strong light-matter interaction and selectively enhanced photocurrent generation. Such enhancement is attributed to the emergence of unique twist-angle-dependent van Hove singularities, which are directly revealed by spatially resolved angle-resolved photoemission spectroscopy. When the energy interval between the van Hove singularities of the conduction and valance bands matches the energy of incident photons, the photocurrent generated can be significantly enhanced (up to ∼ 80 times with the integration of plasmonic structures in our devices). These results provide valuable insight for designing graphene photodetectors with enhanced sensitivity for variable wavelength.
具有超高载流子迁移率和超短光响应时间的石墨烯在超快光探测中显示出显著潜力。然而，单层石墨烯宽泛且微弱的光吸收（约2.3%）阻碍了其在具有高响应度和选择性的光电探测器中的实际应用。在此，我们证明了扭曲双层石墨烯，即由两个具有层间扭曲角的石墨烯单层堆叠而成，表现出强烈的光与物质相互作用，并选择性地增强了光电流产生。这种增强归因于独特的与扭曲角相关的范霍夫奇点的出现，这通过空间分辨角分辨光电子能谱直接揭示。当导带和价带的范霍夫奇点之间的能量间隔与入射光子能量匹配时，产生的光电流可显著增强（在我们的器件中集成等离子体结构时可达约80倍）。这些结果为设计对可变波长具有增强灵敏度的石墨烯光电探测器提供了有价值的见解。
