Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 16: Quantum dots and wires: Optical properties I
HL 16.10: Vortrag
Montag, 25. Februar 2008, 16:30–16:45, ER 164
Optical emission from spin singlet and triplet few electron states of a self-assembled quantum dot molecule — •Emily C. Clark1, Christoph Scheurer2, Hubert Krenner1, Max Bichler1, Gerhard Abstreiter1, and Jonathan J. Finley1 — 1Walter Schottky Institut, Technical University of Munich, 85748 Garching, Germany — 2Lehrstuhl für Theoretische Chemie, Technische Universität München, 85748 Garching, Germany
We report magneto-optical investigations of coupled exciton states in individual quantum dot molecules. The samples investigated consist of a single pair of vertically stacked, self assembled In0.5Ga0.5As dots, embedded into the intrinsic region of an n-type GaAs Schottky photodiode.[1] This structure allows us to tune the electric field along the growth axis, switch on an off coupling between the molecular states and controllably add electrons to the molecule. In the absence of a magnetic field a series of characteristic crossings and anti-crossings are observed in the emission spectrum, as neutral and charged exciton states in the dots couple and form molecular orbitals.[2] The magnetic field is shown to mix the s- and p-orbital states in each dot, giving rise to anti-crossings due to hybridization of the mixed s-p orbital states. From our measurements, we deduce the coupling strengths of the mixed states as a function of the magnetic field and extract information about the molecular electronic structure. Our experimental findings will be compared with calculations of the negatively charged exciton states subject to magnetic fields.[1] Krenner et. al Physical Review Letters, 94, 057402, 2005 [2]Krenner et. al Phys. Rev. Lett. 97, 076403, 2006