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Philipps-Universität Marburg
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Abstract
Today?s semiconductor-electronics and
opto-electronics are mainly based on the Coulomb-interaction
between the charge of electrons. But electrons own beneath
their charge also the spin as an additonal property. The
electron-spin is a pure quantum mechanical property which has
no classical analogon. It can only be in one of the two states
?spin-up? or ?spin-down?, respectively.
About 75 years after the introduction of the spin into physics
by Goudsmith and Uhlenbeck in 1925 and its correct description
in the relativistical quantum mechanics by Dirac in1930, the
property ?spin? gets into the modern semiconductor
and information technology.
With thin metallic film systems,
there have been already succesfull developments in the field of
magneto-electronics, e.g. the GMR- and TMR effects. Also the
?Magnetic Random Acces Memory? (MRAM) is subject to
intense research. All these application make use of the quantum
mechanical property ?spin?, but are base on
metallic systems only. A semiconductor based spin-electronic
(?Spintronic?) has the advantage of easy
integration into the conventional electronics. Also a
connection with opto-electronics is possible.
One of the
main prerequisites for spin-based electronic is the efficient
and controlled injection of carrier spin currents. By coherent
control of two laser light-fields spin-polarized currents can
be generated in semiconductors. These currents are based on the
interference of quantum mechanical (opical) transitions and are
a makroscopic manifestation of a pure quantum mechanical
phenomen, which is shown in this work.
A different approach
to influence spin-related effects in semiconductors is due a
controllable symmetry reduction by internal or external applied
electrical fields in semiconductor heterostructures. The
resulting anisotropic spin-effects are measured by spin quantum
beat spectroscopy in magnetic fields.
The spin-depahsing
mechanism electron-hole pairs with parallel spin-orientation,
so called ?dark excitions? are investigated in
semiconductor quantum dots. Those quantum dots are often
suggested to play a role in a prosper quantum-computing
technology, because of the long decoherece times of their
carrier spins. Dark excitons are excited by two-photon
absorption by an ultrashort laser pulse and the converion of
the dark excitons (J=2) to bright excitons (J=1) is measured
time-resolved under different conditions.Today?s semiconductor-electronics and
opto-electronics are mainly based on the Coulomb-interaction
between the charge of electrons. But electrons own beneath
their charge also the spin as an additonal property. The
electron-spin is a pure quantum mechanical property which has
no classical analogon. It can only be in one of the two states
?spin-up? or ?spin-down?, respectively.
About 75 years after the introduction of the spin into physics
by Goudsmith and Uhlenbeck in 1925 and its correct description
in the relativistical quantum mechanics by Dirac in1930, the
property ?spin? gets into the modern semiconductor
and information technology.
With thin metallic film systems,
there have been already succesfull developments in the field of
magneto-electronics, e.g. the GMR- and TMR effects. Also the
?Magnetic Random Acces Memory? (MRAM) is subject to
intense research. All these application make use of the quantum
mechanical property ?spin?, but are base on
metallic systems only. A semiconductor based spin-electronic
(?Spintronic?) has the advantage of easy
integration into the conventional electronics. Also a
connection with opto-electronics is possible.
One of the
main prerequisites for spin-based electronic is the efficient
and controlled injection of carrier spin currents. By coherent
control of two laser light-fields spin-polarized currents can
be generated in semiconductors. These currents are based on the
interference of quantum mechanical (opical) transitions and are
a makroscopic manifestation of a pure quantum mechanical
phenomen, which is shown in this work.
A different approach
to influence spin-related effects in semiconductors is due a
controllable symmetry reduction by internal or external applied
electrical fields in semiconductor heterostructures. The
resulting anisotropic spin-effects are measured by spin quantum
beat spectroscopy in magnetic fields.
The spin-depahsing
mechanism electron-hole pairs with parallel spin-orientation,
so called ?dark excitions? are investigated in
semiconductor quantum dots. Those quantum dots are often
suggested to play a role in a prosper quantum-computing
technology, because of the long decoherece times of their
carrier spins. Dark excitons are excited by two-photon
absorption by an ultrashort laser pulse and the converion of
the dark excitons (J=2) to bright excitons (J=1) is measured
time-resolved under different conditions.
Review
Metadata
Contributors
Supervisor:
Dates
Created: 2003Issued: 2003-12-22Updated: 2011-08-10
Faculty
Fachbereich Physik
Publisher
Philipps-Universität Marburg
Language
ger
Data types
DoctoralThesis
Keywords
Nonlinear opticsspin-injection , quantumdotsSpin polarized transport in semiconductorsOptical creation of spin polarized carriersSpinströmespin-currentsSpininjektion , Landé-g-Faktor , InP-QuantenpunkteFermi surface: calculations and measurements; effective mass, g factorQuantum dots
DFG-subjects
Nichtlineare Spektroskopie , UltrakurzzeitspektroskopieHalbleiterphysik
DDC-Numbers
530
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Hübner, Jens (128629096): Spin-Effekte von optisch erzeugten Ladungsträgern in Halbleitern. : Philipps-Universität Marburg 2003-12-22. DOI: https://doi.org/10.17192/z2003.0741.
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This item has been published with the following license: In Copyright