Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 6: Quantum dots and wires: Transport properties I

HL 6.11: Talk

Monday, March 27, 2006, 12:45–13:00, BEY 118

Carrier storage time of milliseconds at room temperature in self-organized quantum dots — •A. Marent¹, M. Geller¹, A. P. Vasiev², E. S. Semenova², A. E. Zhukov², V. M. Ustinov², and D. Bimberg¹ — ¹Institut für Festkörperphysik, TU Berlin, Hardenbergstr. 36, 10623 Berlin — ²A. F. Ioffe Physico-Technical Institute, Russian Academy of Sience, Polytekhnicheskaya 26, 194021 St. Petersburg, Russia

Self-organized quantum dots (QDs) are promising building blocks for future memory devices. The first milestone is a carrier retention time in the order of milliseconds at room temperature, the typical refresh time of a dynamic random access memory (DRAM). We showed previously, that holes in InAs/GaAs QDs exhibit a ground state localization energy of about 200 meV. This leads to a storage time at room temperature in the order of nanoseconds, which is not sufficient for a memory device. Here, we studied the carrier storage and emission from InAs/GaAs QDs with an additional AlGaAs barrier with deep level transient spectroscopy (DLTS). The thermal emission from the hole ground states over the entire AlGaAs barrier shows a pronounced peak at 300 K for a reference time of 5 ms. That means, we measure a storage time in the order of milliseconds at room temperature, the crucial DRAM refresh time. In addition, we determined the thermal activation energy for hole emission from the ground states over the entire AlGaAs barrier to ∼580 meV.

The work was partly funded by the SANDiE Network of Excellence of the European Commission, contract number NMP4-CT-2004-500101 and SFB296 of DFG.