Propagation length of mesoscopic photocurrents in a two-dimensional electron gas

Stallhofer, Markus; Kastl, Christoph; Brändlein, Marcel; Karnetzky, Christoph; Schuh, Dieter; Wegscheider, Werner; Holleitner, Alexander W.

doi:10.1103/physrevb.86.115313

Cited by 3 publications

(8 citation statements)

References 44 publications

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“…We determine the characteristic photocurrent length within an edge channel to be several tens of micrometer. This length substantially exceeds the mean free path of photogenerated charge carriers at zero and small magnetic fields [29,30]. Our experiments suggest that the measured length is limited by the effective diffusion length of the photogenerated holes which capacitively control the photocurrent detection at the QPC.…”

Section: Introductionmentioning

confidence: 70%

“…Using a confocal scanning laser microscope with a spatial resolution of ∼900 nm, we excite electron-hole pairs in the source region of the circuit and measure the resulting photocurrent from source to drain across the QPC with standard lock-in techniques. We excite at E photon = 1.550 eV with ΔE FWHM = 8 meV, such that the photocurrent response is maximum, yet the excitation into the second two-dimensional subband of the quantum well can be neglected [29,30].…”

Section: Radio Frequency Scanning Photocurrent Microscopymentioning

confidence: 99%

“…This can be understood in a way that the drain region is connected to the read-out circuit without the high impedance of the mesoscopic circuit. For instance, the radio frequency technique allows resolving the propagation length of mesoscopic photocurrents in a 2DEG which is dominated by electron-electron scattering processes [29,30]. Figure 1(c) depicts the amplitude A OBIC of the photocurrent signal at 40.9 MHz across the QPC (black line), for the laser being focused at a centered position 5 μm from the QPC in the source region.…”

Section: Radio Frequency Scanning Photocurrent Microscopymentioning

confidence: 99%

“…For |B| ⩽ ∼0.5 T, Re OBIC dominates the signal. As discussed in detail in [30], this low-magnetic field regime can be understood by classical cyclotron orbits of the photogenerated electrons in combination with a predominant influence of electron-electron scattering processes. In this regime, the QPC detects the photogenerated, non-equilibrium electrons as they tunnel from source to drain.…”

Section: Radio Frequency Scanning Photocurrent Microscopymentioning

confidence: 99%

“…In this regime, the QPC detects the photogenerated, non-equilibrium electrons as they tunnel from source to drain. With increasing magnetic field, the trajectories of the photogenerated electrons in the source region are less commensurate with the etched, lateral aperture of the QPC and its finite width [30]. This explains why Re OBIC decreases for increasing magnetic fields in the range of |B| ⩽ ∼0.5 T. Consistently, the gate voltage dependence at zero magnetic field (figure 1(c)) demonstrates that the signal A OBIC is dominated by Re OBIC and that Im OBIC is rather negligible.…”

Section: Radio Frequency Scanning Photocurrent Microscopymentioning

confidence: 99%

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Optoelectronic transport through quantum Hall edge states

et al. 2015

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We use GaAs-based quantum point contacts as mesoscopic detectors to locally analyze the flow of photogenerated electrons in a two-dimensional electron gas (2DEG) at perpendicular, quantizing magnetic fields. The 2DEG is formed within a quantum well of a doped GaAs/AlGaAs-heterostructure. We find an optoelectronic signal along the lateral boundaries of the 2DEG, which is consistent with an optically induced quantum transport through quantum Hall edge channels. We demonstrate that photogenerated electrons can be directly injected into an edge channel, transported across several tens of micrometers and read-out on-chip by the quantum point contact.

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Section: Introductionmentioning

confidence: 70%

Section: Radio Frequency Scanning Photocurrent Microscopymentioning

confidence: 99%

Section: Radio Frequency Scanning Photocurrent Microscopymentioning

confidence: 99%

Section: Radio Frequency Scanning Photocurrent Microscopymentioning

confidence: 99%

Section: Radio Frequency Scanning Photocurrent Microscopymentioning

confidence: 99%

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Optoelectronic transport through quantum Hall edge states

et al. 2015

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Ultrafast and Local Optoelectronic Transport in Topological Insulators

Kiemle

Seifert

Holleitner

et al. 2020

Physica Status Solidi (b)

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Recently, topological insulators (TIs) were discovered as a new class of materials representing a subset of topological quantum matter. While a TI possesses a bulk band gap similar to an ordinary insulator, it exhibits gapless states at the surface featuring a spin‐helical Dirac dispersion. Due to this unique surface band structure, TIs may find use in (opto)spintronic applications. Herein, optoelectronic methods are discussed to characterize, control, and read‐out surface state charge and spin transport of 3D TIs. In particular, time‐ and spatially‐resolved photocurrent microscopy at near‐infrared excitation can give fundamental insights into charge carrier dynamics, local electronic properties, and the interplay between bulk and surface currents. Furthermore, possibilities of applying such ultrafast optoelectronic methods to study Berry curvature‐related transport phenomena in topological semimetals are discussed.

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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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Propagation length of mesoscopic photocurrents in a two-dimensional electron gas

Cited by 3 publications

References 44 publications

Optoelectronic transport through quantum Hall edge states

Optoelectronic transport through quantum Hall edge states

Ultrafast and Local Optoelectronic Transport in Topological Insulators

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

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