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Spin relaxation in GaAs/AlxGa1-xAs quantum wells

Spin relaxation in GaAs/AlxGa1-xAs quantum wells
Spin relaxation in GaAs/AlxGa1-xAs quantum wells
Spin dynamics of photoexcited carriers in GaAs/AlxGa1-xAs quantum wells have been investigated in a wafer containing twelve different single quantum wells, allowing full investigation of well-width and temperature dependences with minimal accidental variations due to growth conditions. The behavior at low temperatures is dominated by excitonic effects, confirming results described in detail by others. Between 50 and 90 K there is a transition from excitonic to free-carrier-dominated behavior; both the temperature and time scale of the transition are in excellent agreement with a theoretical model for exciton dissociation. Above 90 K we find two-component spin decays consisting of an unresolved component (faster than 2 ps) associated with exciton dissociation and hole spin-relaxation and a longer-lived component that yields the electron spin-relaxation time. In the free-carrier regime, the electron spin-relaxation rate in wide wells follows that for bulk GaAs, which varies approximately as T2. For narrow wells the rate is approximately independent of temperature and varies quadratically with confinement energy. This behavior is consistent with dominance of the D'yakonov-Perel mechanism of electron-spin relaxation and the expected behavior of the electron mobility. The data show evidence of the influence of electron scattering by interface roughness.
1550-235X
13034-13039
Malinowski, A.
54fd31d4-b510-4726-a8cd-33b6b2ad0427
Britton, R.S.
5c67250e-9690-48f5-9bd9-274d3c88639f
Grevatt, T.
80bacf5f-d7b3-4d06-8840-b88241ac9f11
Harley, R.T.
54613031-f60f-45f4-9b20-e49bcfd53b77
Ritchie, D.A.
83562b7e-0986-4822-9cfe-8c4ac95596c7
Simmons, M.Y.
afb0d316-8916-4911-a356-14182e79545e
Malinowski, A.
54fd31d4-b510-4726-a8cd-33b6b2ad0427
Britton, R.S.
5c67250e-9690-48f5-9bd9-274d3c88639f
Grevatt, T.
80bacf5f-d7b3-4d06-8840-b88241ac9f11
Harley, R.T.
54613031-f60f-45f4-9b20-e49bcfd53b77
Ritchie, D.A.
83562b7e-0986-4822-9cfe-8c4ac95596c7
Simmons, M.Y.
afb0d316-8916-4911-a356-14182e79545e

Malinowski, A., Britton, R.S., Grevatt, T., Harley, R.T., Ritchie, D.A. and Simmons, M.Y. (2000) Spin relaxation in GaAs/AlxGa1-xAs quantum wells. Physical Review B, 62 (19), 13034-13039. (doi:10.1103/PhysRevB.62.13034).

Record type: Article

Abstract

Spin dynamics of photoexcited carriers in GaAs/AlxGa1-xAs quantum wells have been investigated in a wafer containing twelve different single quantum wells, allowing full investigation of well-width and temperature dependences with minimal accidental variations due to growth conditions. The behavior at low temperatures is dominated by excitonic effects, confirming results described in detail by others. Between 50 and 90 K there is a transition from excitonic to free-carrier-dominated behavior; both the temperature and time scale of the transition are in excellent agreement with a theoretical model for exciton dissociation. Above 90 K we find two-component spin decays consisting of an unresolved component (faster than 2 ps) associated with exciton dissociation and hole spin-relaxation and a longer-lived component that yields the electron spin-relaxation time. In the free-carrier regime, the electron spin-relaxation rate in wide wells follows that for bulk GaAs, which varies approximately as T2. For narrow wells the rate is approximately independent of temperature and varies quadratically with confinement energy. This behavior is consistent with dominance of the D'yakonov-Perel mechanism of electron-spin relaxation and the expected behavior of the electron mobility. The data show evidence of the influence of electron scattering by interface roughness.

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More information

Published date: 15 November 2000

Identifiers

Local EPrints ID: 50897
URI: http://eprints.soton.ac.uk/id/eprint/50897
ISSN: 1550-235X
PURE UUID: ea9733e2-fdb4-44ed-a04e-7c5bd947baf2

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Date deposited: 09 Apr 2008
Last modified: 08 Jan 2022 13:02

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Contributors

Author: A. Malinowski
Author: R.S. Britton
Author: T. Grevatt
Author: R.T. Harley
Author: D.A. Ritchie
Author: M.Y. Simmons

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