Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 44: Quantenpunkte und -dr
ähte: Optische Eigenschaften III

HL 44.5: Vortrag

Donnerstag, 27. März 2003, 15:30–15:45, BEY/118

Lateral quantization in single and planarly coupled quantum dots — •Stefan Kaiser, Lukas Worschech, Tobias Mensing und Alfred Forchel — Technische Physik, Uni Wuerzburg

Excitons and biexcitons in single and laterally coupled In_0.1Ga_0.9As/GaAs quantum dots have been investigated by photoluminescence spectroscopy at low temperatures. The quantum dots were realized by electron beam lithography and wet etching with lateral dot diameters between 60 and 150 nm. The coupled quantum dots consist of two closely spaced dots, which are connected by a narrow bridge. The transition energy associated with the recombination of an exciton increases by 5.5 meV and 3.5 meV for single and coupled quantum dots, respectively, when the dot diameter decreases from 150 to 60 nm due to an increasing lateral quantization. The reduced blue shift of the exciton ground state of the coupled quantum dot is associated with an extended exciton state. This assumption is confirmed by magnetooptical investigations. The diamagnetic shift as a measure of the quantum wavefunction perpendicular to the magnetic field of the single exciton state is larger in the coupled quantum dot compared to a single quantum dot of similar diameter.