SPP 1285: Spin-Dependent Electron in GaAs/AlGaAs Nanostructures (III)


The aim of this project within the DFG priority programme 1285 "Semiconductor Spinelectronics" is to investigate spin-dependent ballistic transport in nanoscale GaAs/AlGaAs field-effect heterostructures (FETs) of low spin-orbit coupling, and to extend the experimental studies to InAs/InGaAs field-effect heterostructures with an increased spin-orbit coupling for a direct comparison. Starting materials are modulation doped heterostructures with two-dimensional electron gases of high mobilities (> 10 6 cm 2 /Vs for GaAs-based FETs and >10 5 cm 2 /Vs for InAs-based FETs) from which Aharonov-Bohm ring structures are prepared by electron-beam lithography and wet-chemical etching. Four-terminal measurements of current and voltage characteristics are taken as a function of top voltages and magnetic fields at low temperatures (< 4.2 K). Local nanopatterned top-gates are used to control the electron densities in the electron waveguides of the ring. Quantum point contacts with large subband separations (>5-10 meV) are employed as energy and mode filters and the injection of spin polarised electrons in the ring is planned by using a quantum point contact as spin filter element in inplane magnetic fields. The amplitude and phase of the Aharonov-Bohm conductance oscillations is investigated for different operating modes of the injecting quantum point contact. Up-to-date, the transport in the mode occupation below the first mode of a quantum point contact is discussed with spin-related mechanisms and remains an unresolved issue. The objective is the investigation of spin-related dephasing mechanisms in the electronic quantum transport which is being approached by adding a single-electron transistor with tunable coupling to the ring structure. The transport experiments are accompanied and supported by collaborative research on optically-induced transport phenomena and theoretical calculations from partner groups within the priority programme 1285.
The aim of this project within the DFG priority programme 1285 "Semiconductor Spinelectronics" is to investigate spin-dependent ballistic transport in nanoscale GaAs/AlGaAs field-effect heterostructures (FETs) of low spin-orbit coupling, and to extend the experimental studies to InAs/InGaAs field-effect heterostructures with an increased spin-orbit coupling for a direct comparison. Starting materials are modulation doped heterostructures with two-dimensional electron gases of high mobilities (> 10 6 cm 2 /Vs for GaAs-based FETs and >10 5 cm 2 /Vs for InAs-based FETs) from which Aharonov-Bohm ring structures are prepared by electron-beam lithography and wet-chemical etching. Four-terminal measurements of current and voltage characteristics are taken as a function of top voltages and magnetic fields at low temperatures (< 4.2 K). Local nanopatterned top-gates are used to control the electron densities in the electron waveguides of the ring. Quantum point contacts with large subband separations (>5-10 meV) are employed as energy and mode filters and the injection of spin polarised electrons in the ring is planned by using a quantum point contact as spin filter element in inplane magnetic fields. The amplitude and phase of the Aharonov-Bohm conductance oscillations is investigated for different operating modes of the injecting quantum point contact. Up-to-date, the transport in the mode occupation below the first mode of a quantum point contact is discussed with spin-related mechanisms and remains an unresolved issue. The objective is the investigation of spin-related dephasing mechanisms in the electronic quantum transport which is being approached by adding a single-electron transistor with tunable coupling to the ring structure. The transport experiments are accompanied and supported by collaborative research on optically-induced transport phenomena and theoretical calculations from partner groups within the priority programme 1285.

Projektleitung
Fischer, Saskia Prof. Dr. rer. nat. (Details) (Neue Materialien)

Laufzeit
Projektstart: 10/2011
Projektende: 07/2014

Forschungsbereiche
Elektronische Halbleiter, Bauelemente und Schaltungen, Integrierte Systeme, Experimentelle Physik der kondensierten Materie, Naturwissenschaften

Forschungsfelder
Elektronik, Experimentelle Physik, kondensierte Materie, Neue Materialien, Quanten-/Spinelektronik, Quantentechnologie

Zuletzt aktualisiert 2022-08-09 um 03:07