Charge trapping memory structures with Al2O3 dielectrics as a trapping dielectric are investigated in a metal-Al2O3-Oxide-silicon configuration with a metal gate of high work function. The devices show very good write/erase characteristics, endurance, retention and disturb behaviour. At elevated temperature, devices with an Al2O3 trapping layer are found to have better retention properties than devices with a silicon nitride trapping layer. (c) 2005 Elsevier Ltd. All rights reserved.