scholarly journals Van Hove Singularities and Excitonic Effects in the Optical Conductivity of Twisted Bilayer Graphene

Nano Letters ◽  
2014 ◽  
Vol 14 (6) ◽  
pp. 3353-3357 ◽  
Author(s):  
Robin W. Havener ◽  
Yufeng Liang ◽  
Lola Brown ◽  
Li Yang ◽  
Jiwoong Park
Keyword(s):  
Optical Conductivity ◽  
Bilayer Graphene ◽  
Van Hove Singularities ◽  
Twisted Bilayer Graphene ◽  
Excitonic Effects

scholarly journals Selectively enhanced photocurrent generation in twisted bilayer graphene with van Hove singularity

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Jianbo Yin ◽  
Huan Wang ◽  
Han Peng ◽  
Zhenjun Tan ◽  
Lei Liao ◽  
...  
Keyword(s):  
Twist Angle ◽  
Bilayer Graphene ◽  
Monolayer Graphene ◽  
Valuable Insight ◽  
Strong Light ◽  
Van Hove Singularities ◽  
Spatially Resolved ◽  
Enhanced Sensitivity ◽  
Photocurrent Generation ◽  
Twisted Bilayer Graphene

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.

scholarly journals Splitting of Van Hove singularities in slightly twisted bilayer graphene

2017 ◽  
Vol 96 (15) ◽  
Author(s):  
Si-Yu Li ◽  
Ke-Qin Liu ◽  
Long-Jing Yin ◽  
Wen-Xiao Wang ◽  
Wei Yan ◽  
...  
Keyword(s):  
Bilayer Graphene ◽  
Van Hove Singularities ◽  
Twisted Bilayer Graphene
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