Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 37: Quantum Dots and Wires: Optical Properties III

HL 37.8: Vortrag

Mittwoch, 24. März 2010, 11:30–11:45, H15

Tunable exciton g-factor in height and composition engineered quantum dots — •Vase Jovanov¹, Florian Klotz¹, Emily Clark¹, Daniel Rudolph¹, Johannes Kierig¹, Paul M. Koenraad², Max Bichler¹, Martin S. Brandt¹, Gerhard Abstreiter¹, and Jonathan J. Finley¹ — ¹Walter Schottky Institut, TU München, Am Coulombwall 3, 85748 Garching, Germany — ²Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands

We present experimental and theoretical investigations of the influence of static electric and magnetic fields on the exciton g-factor (g_ex,zz) of self-assembled InGaAs-GaAs quantum dots. The use of a novel growth procedure allows us to precisely control the dot height (h=2-6 nm) by partially capping the dots with GaAs before introducing a growth interruption and annealing step to remove Indium from the growth surface ("In-flush" method). By performing single quantum dot photoluminescence and photocurrent absorption measurements with magnetic fields up to 15T applied parallel to the quantum dot growth axis we show that the g_ex,zz can be tuned from 0.4 to -0.4 by applying static electric fields≤70kV/cm. Microscopically, the effect is caused by pushing the electron and hole components of the exciton wavefunction into different regions of the dot, with differing local In-Ga composition. For the tallest dots (h=6nm) we find that |g_ex,zz| is also influenced by the static magnetic field. Our experimental findings are in good qualitative agreement with detailed 3D eight-band k·p calculations that incorporates the magnetic field in a fully gauge invariant manner.