Memory devices—Non-volatile memories

In this entry, the most important non-volatile memories used for a wide variety of applications are presented, with detailed information on their structural and functional properties. The first part addresses charge-based memories, including read-only memories, electrically programmable read-only memories, electrically erasable and programmable read-only memories, and flash memories. In a broad sense, all them can be considered non-volatile read-only memories, meaning that reading the stored information can be performed in a relatively short time, but programming and erasing require much longer times, if at all possible. The second part of the presentation encompasses non-volatile memories which exhibit similar read/write (R/W) access times, and can thus be regarded as random-access memories to all effects. More specifically, we illustrate magnetic memories, ferroelectric memories, phase-change memories and resistive memories, and discuss their future market perspectives.