Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 48: Poster 2
HL 48.41: Poster
Donnerstag, 26. März 2009, 15:00–17:30, P2
Emission from s- and p-states in self-assembled InAs quantum dots — Andreas Schramm1,2, Christian Heyn2, and •Wolfgang Hansen2 — 1Optoelectronics Research Centre, Tampere University of Technology, Finland — 2Institute of Applied Physics, University of Hamburg, Germany
We study the temperature- and electric-field dependence of the electron emission from charged InAs quantum dots. The semiconductor quantum dots are grown with molecular beam epitaxy on (001) GaAs and embedded in Schottky diodes designed for high-resolution transient capacitance spectroscopy. The emission rates of s- and p-shell electrons are determined at different electric fields controlled by the bias voltage at the Schottky diode. Our data demonstrate that the emission rate not only strongly depends on the shell the carrier is emitted from but also on its charge state. The observed behaviour of the emission rates can be quantitatively understood with a model for thermionic-tunnelling through a Coulomb barrier. The tunnel-barrier height is given by charge state independent s- or p-shell binding energies and its shape is assumed to arise from the Coulomb potential of the dot charge and a bias voltage controlled triangular contribution.