Electron-hole scattering in GaAs quantum wells

Höpfel, R. A.; Shah, Jagdeep; Wolff, Peter; Gossard, A. C.

doi:10.1103/physrevb.37.6941

Cited by 69 publications

(20 citation statements)

References 29 publications

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“…This can be seen by considering that electron-hole scattering is well approximated by ionized impurity scattering. 18 Thus the observed mobility should be similar to that observed in doped samples with densities equal to the photogenerated carrier density. This interpretation does not reconcile the ϳ50% mobility reduction observed for carrier densities of Ͻ5ϫ10 15 cm Ϫ3 .…”

Section: Discussionsupporting

confidence: 59%

Subpicosecond photoconductivity ofIn0.53Ga0.47As: Intervalley s

et al. 1996

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We report on the transient photoconductivity of hot carriers in undoped bulklike In 0.53 Ga 0.47 As observed via time-resolved terahertz far-infrared spectroscopy. For very dilute photoexcitation densities of Ͻ1ϫ10 15 cm Ϫ3 and an initial excess carrier energy of 630 meV, we find that electrons have an effective intervalley L→⌫ return time of 3.1 ps as measured via the increased electrical conductivity associated with ⌫ electrons. In contrast, a total conductivity risetime of ϳ0.5 ps is observed for electrons with initial excess energy insufficient to cause intervalley scattering. The observed frequency dependent conductivity is analyzed via the Drude theory, allowing the determination of the temporal dynamics of the mobility at dilute excitation densities of ϳ1ϫ10 14 cm Ϫ3 .

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Section: Discussionsupporting

confidence: 59%

Subpicosecond photoconductivity ofIn0.53Ga0.47As: Intervalley s

et al. 1996

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“…We argue below that the dependence of on I indicates that the direct force of the electric field on the spin polarization is zero, and that spin waves (or packets) are propelled solely by momentum transfer from the surrounding Fermi sea. The basis of this claim is that the same dependence of mobility on pump intensity is observed when the Fermi sea drives another neutral excitation of the 2DEG, namely packets of e-h density [27,28]. Individual packets of electron and hole density cannot separate in weak applied fields -the constraint of local charge neutrality forces the two charge species drift together at a speed , where is the ambipolar mobility.…”

Section: Temperature Dependence Of Spin Mobilitymentioning

confidence: 95%

Doppler velocimetry of spin propagation in a two-dimensional electron gas

et al. 2011

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Controlling the flow of electrons by manipulation of their spin is a key to the development of spin-based electronics. While recent demonstrations of electrical-gate control in spin-transistor configurations show great promise, operation at room temperature remains elusive. Further progress requires a deeper understanding of the propagation of spin polarization, particularly in the high mobility semiconductors used for devices. Here we report the application of Doppler velocimetry to resolve the motion of spin-polarized electrons in GaAs quantum wells driven by a drifting Fermi sea. We find that the spin mobility tracks the high electron mobility precisely as a function of T.However, we also observe that the coherent precession of spins driven by spin-orbit interaction, which is essential for the operation of a broad class of spin logic devices, breaks down at temperatures above 150 K for reasons that are not understood theoretically.The transistor, the iconic invention of 20 th century science, is a semiconductor device in which the flow of electrons is modulated by voltages applied via electrodes known appropriately as gates. In a conventional transistor the gate electrode controls the number of mobile electrons in the current carrying pathway, or "channel." In pursuit of transistors with faster response and lower rates of energy dissipation, there has been intense investigation aimed at modulating current through manipulation of spin by applied electric fields [1,2], a coupling that occurs because of the spin-orbit (SO) interaction. Recently, gate-controlled modulation of current via SO coupling has been demonstrated in prototype device structures that operate below room temperature [3,4].Further progress towards spintronic logic requires a deeper understanding of the basic physical principles upon which such devices are based. Essentially the question is this: how far, and how fast, can spin polarization propagate in a current-carrying electron gas? This question was first addressed in pioneering work that used magneto-optic imaging to follow the drift of spin polarization packets in real space [5]. These experiments were enabled by the enhanced spin lifetimes (in excess of 10 ns) that arise near the metal-insulator transition of a doped semiconductor at the expense of electron mobility, . However, the high electron gas needed for fast devices is in a very different dynamical regime, where spin lifetimes are ~ 10-100 ps, during which time spin may propagate only 10-100 nm (depending on the temperature, T, and

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“…Since the Shockley-Haynes experiment [1] various groups have studied electron-hole systems and addressed different types of problems. Höpfel et al [2,3] have investigated the electron-hole momentum relaxation in GaAs quantum well (QW) structures. They demonstrated negative absolute mobility of minority carriers as a consequence of electron-hole scattering, the so-called carrier drag effect.…”

Section: Direct Observation Of Hole Edge Channels In a Two Dimensionamentioning

confidence: 99%

Direct Observation of Hole Edge Channels in a Two Dimensional Electron Gas

Paassen¹,

Zrenner²,

Éfros³

et al. 1999

Phys. Rev. Lett.

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We report the direct optical observation of confinement and transport of minority holes in a two dimensional electron gas. In spatially resolved magneto-optical experiments we observe hole confinement at the edge of a two dimensional electron gas and hole transport in edge channels. In a theoretical analysis we show that a repulsive edge potential for holes at the boundary of a two dimensional electron gas is caused by a polaron effect.

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Electron-hole scattering in GaAs quantum wells

Cited by 69 publications

References 29 publications

Subpicosecond photoconductivity ofIn0.53Ga0.47As: Intervalley s

Subpicosecond photoconductivity ofIn0.53Ga0.47As: Intervalley s

Doppler velocimetry of spin propagation in a two-dimensional electron gas

Direct Observation of Hole Edge Channels in a Two Dimensional Electron Gas

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