Electron spin-polarization in p-doped quantum wells

Ferreira, Robson; Roussignol, Philippe; Rolland, P.A.; Bastard, G.; Delalande, Claude; Vinattieri, A.; Weimann, G.

doi:10.1051/jp4:1993532

Cited by 9 publications

(11 citation statements)

References 3 publications

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“…Many works deal with the spin processes of excitons [14][15][16][17][18][19][20][21][22], including the study of the influence of external electric fields [23]. Fewer investigations deal with the spin flip of individual electrons and holes in 2D systems [16,17,[24][25][26]. Extensive theoretical studies have been also done on the spin-flip relaxation of excitons [27][28][29][30] and free carriers [31][32][33][34].…”

Section: Vinamentioning

confidence: 99%

Ultrafast Processes in Semiconductor Structures

Viña

1999

Acta Phys. Pol. A

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We review the dynamics of some of the more relevant optical processes in semiconductor quantum wells. We concentrate on the linear regime and study the time evolution of the light emission, using time-resolved photoluminescence spectroscopy. In intrinsic materials, excitonic effects determine their optical properties. Here we describe the formation and recombination of excitons, and the dependence of these processes on lattice temperature, exciton density, and energy of the excitation light pulses. We also describe the dynamics of the exciton's spin by optical orientation experiments. We discuss the principal mechanisms responsible for the spin flip of the excitons and clarify the role of the exciton localization. Finally, we will show that exciton-exciton interaction produces a breaking of the spin degeneracy in two-dimensional semiconductors. In doped quantum wells, we show that the two spin components of an optically created two-dimensional electron gas are well described by the Fermi-Dirac distributions with a common temperature but different chemical potentials. The rate of the spin depolarization of the electron gas is found to be independent of the mean electron kinetic energy but accelerated by thermal spreading of the carriers.

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Section: Vinamentioning

confidence: 99%

Ultrafast Processes in Semiconductor Structures

Viña

1999

Acta Phys. Pol. A

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“…10 There are evidences that BAP is the strongest spin-flip process in the bulk, 2 as well as in the doped quantum wells ͑QW͒, 4 but there are also claims to the contrary. 5 In reality, the existing experiments are not done in sufficient number and detail to point out to us for sure which is the dominant spin-relaxation channel for electrons in p-doped QW and for holes in n-doped QW. To provide further arguments to help on the analysis of the experimental observations, we present here a study of the BAP process in QW of GaAs/Al x Ga 1Ϫx As doped with acceptor impurities ͑i.e., p-type͒.…”

Section: Introductionmentioning

confidence: 99%

Electron-spin relaxation in p-type quantum wells via the electron-hole exchange interaction:The effects of the valence-band spin mixing and of an applied longitudinal electric field

Maialle

Degani

1997

Phys. Rev. B

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The spin-relaxation time of the photogenerated electrons in p-doped quantum wells of GaAs is calculated. The spin-flip mechanism investigated is due to the electron-hole scattering by the exchange interaction. We have shown that the inclusion of the spin mixing of the valence holes has a dual effect. On one hand, it increases the spin-flip scattering rate by enlarging the hole density of states. On the other hand, the exchange strength weakens due to the valence spin mixing. The combined effect is a partial compensation, leaving the spin-relaxation times of the electrons similar to those obtained assuming holes having pure-spin states. We have also investigated the changes on the spin relaxation brought about by an applied electric field along the quantum well growth direction, and we have calculated longer spin relaxation as the field strength increases. Such behavior is characteristic of the exchange spin-flip channel and, if experimentally observed, it will indicate the dominant role played by the type of spin relaxation we have studied in this work.

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“…It is also well established that the spin relaxation and the polarization profile are given by the combined effects of two factors: the electronic structure and the joint density of states involved in the transitions. 12 The time-resolved results, however, are not conclusive: spin relaxation times of 4 ps 2 as well as 1 ns 3 have been measured for holes in n-type-doped QW's while spin relaxation times of 150 ps 2 and 1 ns 4 were found for electrons in p-type-doped QW's. Slower spin relaxation was reported for high-energy electrons compared to low-energy electrons in an n-type-doped multiple-QW sample.…”

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confidence: 99%

“…The influence of a two-dimensional ͑2D͒ electron or hole gas in the carrier spin relaxation in semiconductor quantum wells ͑QW's͒ has been experimentally [1][2][3][4][5][6] and theoretically [7][8][9][10][11] investigated in recent years. The experimental work explored both continuous-wave ͑CW͒ and timeresolved regimes.…”

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Electron-spin polarization near the Fermi level inn-type modulation-doped semiconductor quantum wells

et al. 1999

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We study the spin polarization of optically created electrons near the Fermi energy in an n-type modulationdoped single quantum well. In our system the Fermi level is slightly above the second confined conduction subband. The results reveal that electrons optically created close to the Fermi level partially conserve their spin polarization, despite the presence of the electron gas. Data obtained by changing the excitation intensity show that exchange interaction among optically created electrons and holes dominates the spin flip processes in the vicinity of the Fermi edge. ͓S0163-1829͑99͒51412-4͔ P C decreases from 45% to 15% as the intensity increases RAPID COMMUNICATIONS PRB 59 R7815 ELECTRON-SPIN POLARIZATION NEAR THE FERMI. . .

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Electron spin-polarization in p-doped quantum wells

Cited by 9 publications

References 3 publications

Ultrafast Processes in Semiconductor Structures

Ultrafast Processes in Semiconductor Structures

Electron-spin relaxation in p-type quantum wells via the electron-hole exchange interaction:The effects of the valence-band spin mixing and of an applied longitudinal electric field

Electron-spin polarization near the Fermi level inn-type modulation-doped semiconductor quantum wells

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