Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 52: Quantum dots and wires: Optical properties IV
HL 52.9: Vortrag
Freitag, 31. März 2006, 13:00–13:15, POT 151
Optically Probing Hole Spin Dynamics in InGaAs Quantum Dots — •Stefan Schaeck, Dominik Heiss, Miro Kroutvar, Max Bichler, Dieter Schuh, Gerhard Abstreiter, and Jonathan J. Finley — Walter Schottky Institut, Am Coulombwall 3, 85748 Garching, Germany
Recently, we presented an optically driven spin memory device that enables selective generation, storage and readout of single electron spins in InGaAs self assembled quantum dots (QDs). This device operates via optical charging of a sub ensemble of dots via polarized optical excitation and selective exciton ionisation using an internal electric field. Using such techniques we studied the electron spin lifetime (T1) as a function of Zeeman energy and lattice temperature and deduced the dominant relaxation mechanisms for self assembled QDs.
Lately, we have extended our investigations to a modified device design that enables investigation of the dynamics of optically generated holes. In strong contrast to electron storage experiments, hole storage samples reveal no optical polarization memory effect for storage times of 0.5 µ s and magnetic fields up to ∼ 12 T. These findings contrast strongly with our findings for electrons, indicating that the hole spin decays over much faster timescales. The hole (T1) time in QDs has been controversially discussed in the literature; some theories indicating that it can be comparable to electrons whilst others predict orders of magnitude faster relaxation. Our results provide, much needed, experimental data for comparison with theory.