Carrier storage time of milliseconds at room temperature in self-organized quantum dots

Thermally activated hole emission from differently charged InAs∕GaAs quantum dots (QDs) was investigated by using deep level transient spectroscopy. In a sample with an additional AlGaAs barrier below the QD layer, a thermal activation energy of 560meV for hole emission from the QD ground states over the AlGaAs barrier is obtained. This large activation energy leads to a hole storage time at room temperature of about 5ms, which is in the order of magnitude of a typical dynamic random access memory (DRAM) refresh time.