Journal
PHOTONICS
Volume 9, Issue 11, Pages -Publisher
MDPI
DOI: 10.3390/photonics9110867
Keywords
silicon photodetector; twisted bilayer graphene; silicon photonics
Categories
Funding
- National Natural Science Foundation of China [62205114]
- Key Research and Development Program of Hubei Province [2022BAA001]
- Starting Research Fund from the Huazhong University of Science and Technology [3004182179]
- National Undergraduate Training Projects for Innovation and Entrepreneurship [5003182104]
- VILLUM FONDEN [00025298]
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This article presents a design for a silicon/TBG hybrid photodetector with high responsivity and bandwidth. By tuning the twisted angle of TBG and utilizing a silicon slot waveguide, the absorption and mode overlap are enhanced. This design not only outperforms previously reported silicon/monolayer graphene photodetectors, but also paves the way for practical applications of graphene-based silicon optoelectronic devices.
Graphene/silicon hybrid photodetector operating at communication wavelength has attracted enormous attention recently due to its potential to realize bandwidth larger than 100 GHz. However, the responsivity is intrinsically limited by the low absorption from the atomic-thick graphene monolayer, which imposes significant obstacles towards its practical application. Although plasmonic structures has been widely applied to enhance the responsivity, it may induce the metallic absorption thus limit the responsivity lower than 0.6 A/W. Twisted bilayer graphene (TBG) has been reported to hold the ability to dramatically enhance the optical absorption due to the unique twist-angle-dependent van Hove singularities. In this article, we present a design of a silicon/TBG hybrid photodetector with a responsivity higher than 1 A/W and bandwidth exceeding 100 GHz. The enhanced responsivity is achieved by tuning the twisted angle of TBG to increase the absorption within the 1550 nm as well as utilizing the silicon slot waveguide to boost the mode overlap with TBG. The fabrication process of proposed design is also discussed demonstrating the advantages of low fabrication complexity. The proposed silicon/TBG photodetector could not only exhibit superior performance compared to previously reported silicon/monolayer graphene photodetector, but also pave the way for the practical application of graphene-based silicon optoelectronic devices.
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