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Biomedical subjects

G Abstreiter

Publications and source records attributed to G Abstreiter.

At least 19 recordsLinked to original sources
PubMed2000

Ultrafast optical spectroscopy of large-momentum excitons in GaAs.

Highly energetic excitons with wave vectors much larger than that of an absorbed photon are excited in thin GaAs films. We observe propagation beats between three polariton modes up to 300 meV above the absorption edge employing femtosecond transmission spectroscopy. The dispersion relations of the coherent excitations are measured. Ultrafast exciton damping via scattering with nonequilibrium carriers and with phonons is investigated. The dynamics is found to deviate strongly from the relaxation of free carriers. Theoretical simulations are in quantitative agreement with the data.

Journal Article↗
PubMed1997

Coupled quantum dots fabricated by cleaved edge overgrowth: from artificial atoms to molecules

Atomically precise quantum dots of mesoscopic size have been fabricated in the gallium arsenide-aluminum gallium arsenide material system by cleaved edge overgrowth, with a high degree of control over shape, composition, and position. The formation of bonding and antibonding states between two such "artificial atoms" was studied as a function of quantum dot separation by microscopic photoluminescence (PL) spectroscopy. The coupling strength within these "artificial molecules" is characterized by a systematic dependence of the separation of the bonding and antibonding levels, and of the PL linewidth, on the "interatomic" distance. This model system opens new insights into the physics of coupled quantum objects.

Journal Article↗