Ultrafast Photodetection in the Quantum Wells of Single AlGaAs/GaAs-Based Nanowires

Abstract

We investigate the ultrafast optoelectronic properties of single Al0.3Ga0.7As/GaAs core-shell nanowires. The nanowires contain GaAs-based quantum wells. For a resonant excitation of the quantum wells, we find a picosecond photocurrent which is consistent with an ultrafast lateral expansion of the photogenerated charge carriers. This Dember-effect does not occur for an excitation of the GaAs-based core of the nanowires. Instead, the core exhibits an ultrafast displacement current and a photothermoelectric current at the metal Schottky contacts. Our results uncover the optoelectronic dynamics in semiconductor core-shell nanowires comprising quantum wells, and they demonstrate the possibility to use the low-dimensional quantum well states therein for ultrafast photoswitches and photodetectors.

Surface State-Dominated Photoconduction and THz Generation in Topological Bi2Te2Se Nanowires

“…In principle, a lateral photo-Dember effect is also consistent with the spatial variation of the THz phase at the contacts. 40,41 For a lateral photo-Dember effect, however, the THz phase should change polarity at the very end of the elongated part of the BTS nanowire, which we do not detect. Furthermore, the electron and hole mobilities are rather similar in bismuth chalcogenides, which makes photo-Dember effects unlikely in these materials.…”

“…The latter rely on the ambipolar diffusion of electrons and holes due to distinct charge-carrier mobilities. 37−41 Moreover, a THz radiation can be generated by ultrafast transient photocurrents, where optically excited charge carriers are accelerated in an intrinsic electric field at the material’s surface or in the depletion area caused by a Schottky barrier at a metal–semiconductor interface. 38,42−44 For BTS, an optical rectification effect can only occur in the topological surface states, as the second-order nonlinear susceptibility χ (2) does not vanish when the inversion symmetry is broken.…”

High‐Responsivity Photodetection by a Self‐Catalyzed Phase‐Pure p‐GaAs Nanowire

“…In recent years, semiconductor nanowires (NWs) have received tremendous attention because of their enormous potential applications in nanoscale electronics and optoelectronics devices such as photodetectors (PDs), single electron transistors, single photon detectors, tunneling diodes, and nanolasers . Reduced dimensionality, large surface‐to‐volume ratio, and strong light–matter interaction make the NWs a solid candidate for optoelectronic applications .…”

PtAu alloy nanoflowers on 3D porous ionic liquid functionalized graphene-wrapped activated carbon fiber as a flexible microelectrode for near-cell detection of cancer

“…[1][2][3] In addition, the high temporal resolution for fast electron/mass transfer due to nonplanar diffusion [4][5][6] and the intrinsic mechanical and deformational characteristics enable such electrodes to be rolled up and incorporated into compact electrochemical sensor systems. The miniaturized integrated sensor devices based on fiber microelectrodes open the possibility of measuring miniscule body fluid sample volumes for in vitro analysis and minimally invasive in vivo clinical analysis; [7][8][9] such devices also provide new insight into near-cell and even intracellular biological signals that can be isolated from the surroundings.…”