Circularly polarized luminescence microscopy for the imaging of charge and spin diffusion in semiconductors

Favorskiy, I.; Vu, Duong; Peytavit, E.; Arscott, S.; Paget, D.; Rowe, A. C. H.

doi:10.1063/1.3493047

Cited by 43 publications

(64 citation statements)

References 24 publications

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“…Curve a, taken at the same low power as Fig. 1, reveals the expected polarization decrease caused by spin-lattice relaxation during transport [17]. Note that the low power electronic polarization at r = 0, P lp (0) = 45 % is almost equal to the initial polarization P i .…”

Section: A Methodsmentioning

confidence: 83%

“…1 and has been presented in more detail elsewhere [17]. Circularly-polarized light excitation at 1.59 eV is focused to a Gaussian spot of half width ω = 0.6 µm.…”

Section: A Methodsmentioning

confidence: 99%

“…The second possible effect induced by degeneracy is a spin-dependent increase of the mobility, as described by Eq. (17) and is a direct consequence of Pauli exclusion due to which elementary scattering processes are forbidden if the final state is already occupied by an electron of the same spin. The diffusion constants for spins ± are finally given by…”

Section: Relevant Mechanisms For Spin Transport Under Local Excitmentioning

confidence: 99%

“…Here, we present a theoretical and experimental investigation of the effect of degeneracy on spin transport in p + GaAs using a polarized microluminescence method in which the spin polarization is measured as a function of distance from a local, diffraction-limited excitation spot [17][18][19]. This study reveals that the dominant effect of degeneracy is the spin dependence of diffusion.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the Pauli principle on photoelectron spin transport inp+GaAs

et al. 2015

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In p + GaAs thin films, the effect of photoelectron degeneracy on spin transport is investigated theoretically and experimentally by imaging the spin polarization profile as a function of distance from a tightly-focussed light excitation spot. Under degeneracy of the electron gas (high concentration, low temperature), a dip at the center of the polarization profile appears with a polarization maximum at a distance of about 2 µm from the center. This counterintuitive result reveals that photoelectron diffusion depends on spin, as a direct consequence of the Pauli principle. This causes a concentration dependence of the spin stiffness while the spin dependence of the mobility is found to be weak in doped material. The various effects which can modify spin transport in a degenerate electron gas under local laser excitation are considered. A comparison of the data with a numerical solution of the coupled diffusion equations reveals that ambipolar coupling with holes increases the steady-state photo-electron density at the excitation spot and therefore the amplitude of the degeneracy-induced polarization dip. Thermoelectric currrents are predicted to depend on spin under degeneracy (spin Soret currents), but these currents are negligible except at very high excitation power where they play a relatively small role. Coulomb spin drag and bandgap renormalization are negligible due to electrostatic screening by the hole gas.

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Section: A Methodsmentioning

confidence: 83%

“…1 and has been presented in more detail elsewhere [17]. Circularly-polarized light excitation at 1.59 eV is focused to a Gaussian spot of half width ω = 0.6 µm.…”

Section: A Methodsmentioning

confidence: 99%

Section: Relevant Mechanisms For Spin Transport Under Local Excitmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of the Pauli principle on photoelectron spin transport inp+GaAs

et al. 2015

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“…1). The sample is excited at its center by a tightly-focused laser along the z direction such that steady-state imaging of the luminescence intensity enables us to monitor the diffusion profile of minority carriers 10 . The resulting profiles are interpreted using two distinct and complementary approaches: i) a numerical resolution of the coupled diffusion equations for electrons and holes, and ii) a simple qualitative estimate of the electron concentration at the center which yields the power dependence of the luminescence thereby permitting D a to be evaluated as a function of photo- electron concentration.…”

Section: Introductionmentioning

confidence: 99%

Imaging ambipolar diffusion of photocarriers in GaAs thin films

Paget

Cadiz

Rowe

et al. 2012

Journal of Applied Physics

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Images of the steady-state luminescence of passivated GaAs self-standing films under excitation by a tightly-focussed laser are analyzed as a function of light excitation power. While unipolar diffusion of photoelectrons is dominant at very low light excitation power, an increased power results in a decrease of the diffusion constant near the center of the image due to the onset of ambipolar diffusion. The results are in agreement with a numerical solution of the diffusion equations and with a physical analysis of the luminescence intensity at the centre of the image, which permits the determination of the ambipolar diffusion constant as a function of electron concentration.

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Fundamentals, Advances, and Artifacts in Circularly Polarized Luminescence (CPL) Spectroscopy

Kitzmann,

Freudenthal,

Reponen

et al. 2023

Advanced Materials

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Objects are chiral when they cannot be superimposed with their mirror image. Materials can emit chiral light with an excess of right‐ or left‐handed circular polarization. This circularly polarized luminescence (CPL) is key to promising future applications, such as highly efficient displays, holography, sensing, enantiospecific discrimination, synthesis of drugs, quantum computing, and cryptography. Here, a practical guide to CPL spectroscopy is provided. First, the fundamentals of the technique are laid out and a detailed account of recent experimental advances to achieve highly sensitive and accurate measurements is given, including all corrections required to obtain reliable results. Then the most common artifacts and pitfalls are discussed, especially for the study of thin films, for example, based on molecules, polymers, or halide perovskites, as opposed to dilute solutions of emitters. To facilitate the adoption by others, custom operating software is made publicly available, equipping the reader with the tools needed for successful and accurate CPL determination.

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Circularly polarized luminescence microscopy for the imaging of charge and spin diffusion in semiconductors

Abstract: Room temperature electronic diffusion is studied in 3 m thick epitaxial p+ GaAs lift-off films using a novel circularly polarized photoluminescence microscope. The method is equivalent to using a standard optical microscope and provides a contactless means to

Cited by 43 publications

References 24 publications

Effect of the Pauli principle on photoelectron spin transport inp+GaAs

Effect of the Pauli principle on photoelectron spin transport inp+GaAs

Imaging ambipolar diffusion of photocarriers in GaAs thin films

Fundamentals, Advances, and Artifacts in Circularly Polarized Luminescence (CPL) Spectroscopy

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