Towards an universal memory based on self-organized quantum dots

Abstract

A concept of a memory device based on self-organized quantum dots (QDs) is presented, which has the potential to fulfill the requirements of an universal memory. We demonstrate here a hole storage time of 1.6 s at room temperature in InAs/GaAs QDs with an additional Al0.9Ga0.1As barrier. This value is already three orders of magnitude longer than the typical DRAM refresh time. The connection between localization energy and storage time for different QD/matrix material combinations enables us to predict a retention time of more than 10 years in In(Ga)Sb/AlAs QDs, like in a Flash memory. Furthermore, we demonstrate a very fast write time below 20 ns for our memory concept in GaSb/GaAs QDs around 100 K. The write time is at the moment only limited by the parasitic cut off frequency of the RC low pass. Hence, an universal QD-based Flash memory-having a storage time in the order of years in combination with a fast write access time below 20 ns-seems feasible. (c) 2007 Elsevier B.V. All rights reserved.