Photodetector Based on Twisted Bilayer Graphene/Silicon Hybrid Slot Waveguide with High Responsivity and Large Bandwidth

Abstract

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.

Twisted Bilayer Graphene: A Journey Through Recent Advances and Future Perspectives

“…The prepared device is illustrated in Figure 11b. [ 147 ] An energy‐resolving single photon detector was demonstrated theoretically based on magic angle bilayer graphene, and its calorimetric photoresponse and detection limits are estimated (Figure 11c). [ 148 ]…”

“…Reproduced under terms of the CC‐BY license. [ 147 ] Copyright 2022, The Authors, published by MDPI. c) Single photon detection in magic angle twisted graphene.…”

“…b) Twisted bilayer graphene/silicon hybrid photodetector. Reproduced under terms of the CC-BY license [147]. Copyright 2022, The Authors, published by MDPI.…”

Voltage-tunable graphene-InP schottky photodetector with enhanced responsivity using plasmonic waveguide integration

“…The weak light absorption in graphene arises from out-of-plane optical interactions between light and atomically thin graphene in the top-illuminated device structure. Therefore, various approaches have been proposed to enhance light-graphene interactions, such as integrating graphene into optical microcavities to interact with light repeatedly [17,18], depositing metallic nanoparticles on graphene to increase light absorption via surface plasmon excitation [19,20], combining graphene with high absorption materials in heterostructure designs [13,14,16], and using graphene in planar optical waveguides to guide light through in-plane light-graphene interactions [21][22][23][24]. The aim is to take advantage of graphene's unique optical properties by engineering structures and materials that can strongly interact with light.…”

Ab initio calculations of low-energy quasiparticle lifetimes in bilayer graphene

“…Bilayer graphene (BLG) has attracted much attention due to its unique fundamental properties as well as its potential for applications in electronics [1], chemical sensing [2], and optoelectronics [3]. For these applications the lifetime of quasiparticles (QPs) plays an important role because it affects the transport properties of electrons through the material and may even determine the current through BLGbased devices.…”