title: Selectively enhanced photocurrent generation in twisted bilayer graphene with van Hove singularity.
abstract: 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.
authors.affiliation: 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.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Yin
authors.affiliation: 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.
authors.forename: Huan
authors.initials: H
authors.lastname: Wang
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
authors.forename: Han
authors.initials: H
authors.lastname: Peng
authors.affiliation: 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.|Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
authors.forename: Zhenjun
authors.initials: Z
authors.lastname: Tan
authors.affiliation: 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.
authors.forename: Lei
authors.initials: L
authors.lastname: Liao
authors.affiliation: 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.
authors.forename: Li
authors.initials: L
authors.lastname: Lin
authors.affiliation: 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.|Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Sun
authors.affiliation: Stanford Nano Shared Facilities, Stanford University, Stanford, California 94305, USA.
authors.forename: Ai Leen
authors.initials: AL
authors.lastname: Koh
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
authors.forename: Yulin
authors.initials: Y
authors.lastname: Chen
authors.affiliation: 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.
authors.forename: Hailin
authors.initials: H
authors.lastname: Peng
authors.affiliation: 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.
authors.forename: Zhongfan
authors.initials: Z
authors.lastname: Liu