The QD-Flash: a quantum dot-based memory device

We demonstrate the large potential of III–V compound semiconductors for a novel type of Flash memory. The concept is based on self-organized III–V quantum dots (QDs). Here the advantages of the most important semiconductor memories, the dynamic random access memory and the Flash are merged. A non-volatile memory with fast access times (<10 ns) and good endurance (>1015 write/erase cycles) as an ultimate solution seems possible. A storage time of 1.6 s at 300 K in InAs/GaAs QDs with an additional Al0.9Ga0.1As barrier was demonstrated and a retention time of 106 years is predicted by us for GaSb QDs in an AlAs matrix. In addition, a minimum write time of 6 ns is obtained for InAs/GaAs QDs. First prototypes with all-electrical data access prove the feasibility of the concept. The stored information is read-out by a two-dimensional hole gas underneath the QD layer. Time-resolved drain-current measurements demonstrate the memory operations