Ultrafast and Local Optoelectronic Transport in Topological Insulators

Kiemle, Jonas; Seifert, Paul; Holleitner, Alexander W.; Kastl, Christoph

doi:10.1002/pssb.202000033

Cited by 19 publications

(11 citation statements)

References 139 publications

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“…Importantly, the transfer curves are highly reproducible with negligible hysteresis at low temperature (see Figure S5 in the Supporting Information). To also access the Dirac point physics of a single BTS/graphene heterojunction, we use a local laser excitation of a single BTS domain and measure the resulting global current into the contacts (turquoise curve in Figure a) . The photocurrent shows a characteristic sign reversal attributable to a photothermoelectric effect of the BTS/graphene interface .…”

Section: Resultsmentioning

confidence: 99%

Gate-Tunable Helical Currents in Commensurate Topological Insulator/Graphene Heterostructures

et al. 2022

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van der Waals heterostructures made from graphene and three-dimensional topological insulators promise very high electron mobilities, a nontrivial spin texture, and a gate-tunability of electronic properties. Such a combination of advantageous electronic characteristics can only be achieved through proximity effects in heterostructures, as graphene lacks a large enough spin–orbit interaction. In turn, the heterostructures are promising candidates for all-electrical control of proximity-induced spin phenomena. Here, we explore epitaxially grown interfaces between graphene and the lattice-matched topological insulator Bi2Te2Se. For this heterostructure, spin–orbit coupling proximity has been predicted to impart an anisotropic and electronically tunable spin texture. Polarization-resolved second-harmonic generation, Raman spectroscopy, and time-resolved magneto-optic Kerr microscopy are combined to demonstrate that the atomic interfaces align in a commensurate symmetry with characteristic interlayer vibrations. By polarization-resolved photocurrent measurements, we find a circular photogalvanic effect which is drastically enhanced at the Dirac point of the proximitized graphene. We attribute the peculiar gate-tunability to the proximity-induced interfacial spin structure, which could be exploited for, e.g., spin filters.

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Section: Resultsmentioning

confidence: 99%

Gate-Tunable Helical Currents in Commensurate Topological Insulator/Graphene Heterostructures

et al. 2022

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“…Lastly, we note that the above formalism applies strictly only to homogeneous media under a homogeneous excitation [88]. For nanoscale materials and devices, local anisotropies, such as edges, metal contacts, built-in potentials, or density gradients from a focused excitation, can give rise to a modified photoresponse due to local ballistic, drift, and diffusion currents [14,47,[135][136][137][138][139][140].…”

Section: General Symmetry Considerations For Light-driven Currentsmentioning

confidence: 99%

“…chirality results in helicity-driven Hall currents, which arise from the underlying Berry curvature monopoles of the Weyl points (Section 3.3). Controlling the flow of charge, spin, and momentum in van der Waals materials by optical means can be utilized in (opto-) spintronic devices to inject, manipulate, or detect spin, charge, and orbital currents [14,15,137,141].…”

Section: Photon Helicity-driven Currentsmentioning

confidence: 99%

Light-field and spin-orbit-driven currents in van der Waals materials

et al. 2020

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AbstractThis review aims to provide an overview over recent developments of light-driven currents with a focus on their application to layered van der Waals materials. In topological and spin-orbit dominated van der Waals materials helicity-driven and light-field-driven currents are relevant for nanophotonic applications from ultrafast detectors to on-chip current generators. The photon helicity allows addressing chiral and non-trivial surface states in topological systems, but also the valley degree of freedom in two-dimensional van der Waals materials. The underlying spin-orbit interactions break the spatiotemporal electrodynamic symmetries, such that directed currents can emerge after an ultrafast laser excitation. Equally, the light-field of few-cycle optical pulses can coherently drive the transport of charge carriers with sub-cycle precision by generating strong and directed electric fields on the atomic scale. Ultrafast light-driven currents may open up novel perspectives at the interface between photonics and ultrafast electronics.

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“…Recently, topological insulators (TIs), emerging as a new quantum state of matter, have drawn enormous interest in physics, materials science, electronics, and other branches of science due to their insulating or semiconducting properties in bulk and metallic Dirac states at the surface. , The helical structure of the topological surface states is protected by time-reversal symmetry, preventing backscattering. As a result, TIs have high carrier mobility and robust transport properties under ambient conditions containing nonmagnetic defect states and dislocations .…”

Section: Introductionmentioning

confidence: 99%

Ultrabroadband Absorption and High-Performance Photodetection in Europium-Doped 2D Topological Insulator Bi₂Se₃ Nanosheets

Paul

Hossain

Mia

et al. 2021

ACS Appl. Nano Mater.

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In the pursuit of materials with exceptional optoelectronic functionalities in the visible to mid-IR region, the topological insulators are very promising because they have unique Dirac-like surface states and high light-absorption properties. Herein, we report on a low-temperature, facile, solution-processable method for the synthesis of undoped and Eu-doped 2D layered Bi 2 Se 3 nanosheets (NSs) with exceptional optical functionalities. 2D geometry provides highly effective light absorption and efficient charge transportation via topologically protected surface states of Bi 2 Se 3 NSs. Our study reveals that as-grown Bi 2 Se 3 NSs possess major native defects, particularly the Se vacancies that are responsible for ultrabroadband absorption and bulk conduction. Interestingly, Eu doping in Bi 2 Se 3 partially compensates the intrinsic defects, and the Eu-doped Bi 2 Se 3 NSs show reduced band gap and very high absorption coefficient (2.87 × 10 5 cm −1 ) over the broad range of 400−2500 nm. We achieve a lower dark current and a higher photocurrent with increasing doping concentration. Interestingly, the undoped Bi 2 Se 3 NSs exhibited negative photoconductivity, which is completely suppressed in the Eu-doped Bi 2 Se 3 NSs due to the reduction in trapping sites. The role of defects in the ultrabroadband absorption and high photoconductivity was elucidated through the rapid thermal annealing studies. To demonstrate its application, we fabricate a planar photodetector using the Eu-doped 2D Bi 2 Se 3 NSs and investigate device characteristics at specific wavelengths 405, 657, and 808 nm. The device with undoped Bi 2 Se 3 NSs shows the highest photoresponsivity at 405 nm, while the Eu-doped NSs show superior performance at 657 and 808 nm. Additionally, the doped photodetectors possess broadband and high responsivity/ detectivity with a peak responsivity of 130 A/W and a peak detectivity of 1.482 × 10 13 Jones, which are the highest among the reported values. The present report demonstrates an effective strategy to develop ultrabroadband and high-performance optoelectronic applications of doped 2D topological insulators.

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Ultrafast and Local Optoelectronic Transport in Topological Insulators

Cited by 19 publications

References 139 publications

Gate-Tunable Helical Currents in Commensurate Topological Insulator/Graphene Heterostructures

Gate-Tunable Helical Currents in Commensurate Topological Insulator/Graphene Heterostructures

Light-field and spin-orbit-driven currents in van der Waals materials

Ultrabroadband Absorption and High-Performance Photodetection in Europium-Doped 2D Topological Insulator Bi₂Se₃ Nanosheets

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Ultrafast and Local Optoelectronic Transport in Topological Insulators

Cited by 19 publications

References 139 publications

Gate-Tunable Helical Currents in Commensurate Topological Insulator/Graphene Heterostructures

Gate-Tunable Helical Currents in Commensurate Topological Insulator/Graphene Heterostructures

Light-field and spin-orbit-driven currents in van der Waals materials

Ultrabroadband Absorption and High-Performance Photodetection in Europium-Doped 2D Topological Insulator Bi2Se3 Nanosheets

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Product

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Ultrabroadband Absorption and High-Performance Photodetection in Europium-Doped 2D Topological Insulator Bi₂Se₃ Nanosheets