Regensburg 2000 – scientific programme

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HL: Halbleiterphysik

HL 25: Quantenpunkte (optische Eigenschaften)

HL 25.12: Talk

Wednesday, March 29, 2000, 18:45–19:00, H15

Normal-incident intersubband photocurrent spectroscopy on InAs/GaAs quantum dots — •L. Chu, A. Zrenner, G. Böhm, and G. Abstreiter — Walter Schottky Institut, TU München, Am Coulombwall, D-85748 Garching

Intersubband transitions between electronic states in GaAs quantum wells are observed only with light polarized along the confinement potential direction. This polarization selection rule implies strong limitations for practical applications, since normal incidence absorption is usually forbidden for electron systems. In contrast to quantum wells, the self-assembled quantum dots exhibit a three-dimensional confinement potential for charge carriers, hence, the polarization selection rules for intersubband transitions in quantum dots should be altered.

We report on intersubband photocurrent spectroscopy on self-assembled InAs/GaAs quantum dots both in normal-incidence and in multi-pass waveguide geometry. The bound-to-continuum transitions in the conduction band have been successfully measured with a n-i-n device structure. The transition energies were in the spectral range between 200-500 meV. Polarization dependent measurements show that the intersubband transitions in the InAs quantum dots are nearly independent of the polarization of the incoming radiation, which is obviously a strong advantage over the conventional quantum well photodetectors.