Flash Memory

Flash memory is memory which retains its contents even after power is removed.

Flash memory is a form of EAPROM (Electrically Alterable Programmable Read-Only Memory).

Each bit of data in a flash memory device is stored in a transistor called a floating gate. The floating gate can only be accessed though another transistor, the control gate.

The process the control gate uses to access the floating gate is a field emission phenomenon known as Fowler-Nordheim tunneling. Tunneling allows voltage to flow from the control gate to the floating gate through the dielectric layer of oxide which separates them.

Popular flash memory devices include:

• Sony's Memory Stick
• Compact Flash
• SDCard
• MultiMediaCard (MMC)