Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 48: Quantenpunke und -dr
ähte: Transporteigenschaften III

HL 48.1: Vortrag

Donnerstag, 27. März 2003, 15:15–15:30, BEY/81

450 meV hole ground state energy in GaSb/GaAs quantum dots — •Martin Geller, Christian Kapteyn, Erik Stock, Lutz Müller-Kirsch, Robert Heitz, and Dieter Bimberg — Institut für Festkörperphysik, TU Berlin, Hardenbergstr. 36, D-10623 Berlin

Self-organized semiconductor quantum dots (QDs) are promising candidates for ultimate memory cells which allow to store information by means of single charge carriers. For memory applications an important issue is the charge carrier retention time at room temperature. GaSb/GaAs QDs show type-II band alignment and the confined hole states should hence exhibit large localization energies, promising long retention times.

The hole confinement in GaSb/GaAs QDs [1] is investigated experimentally by deep level transient spectroscopy (DLTS) and admittance spectroscopy, indeed demonstrating a hole localization energy of about 450 meV. Detailed bias-dependent investigations allow to study state filling and Coulomb charging effects, which lower the thermal activation energy. The hole retention time at room temperature is extrapolated to be in the microsecond range, about five orders of magnitude longer than in In(Ga)As QDs. Therefore, the GaSb/GaAs QD system is a promising to achieve sufficiently long storage times in future QD memory devices.

This work was funded by the Nanomat project of the European Commission Growth Programme, contract number G5RD-CT-00545, INTAS project 2001-774, and SFB 296 of DFG.

[1] L. Müller-Kirsch et al., Appl. Phys Lett. 78, 1418 (2001)