Tunnel release, also called Fowler-Nordheim tunnel release, is the process by which data is erased from NAND flash memory.
Fowler-Nordheim tunneling involves electrons passing through a barrier in the presence of a high electric field. During erase operations on NAND flash media, the electrons tunnel through a thin dielectric material to change the electronic charge on a floating gate associated with a memory cell. A memory cell’s bit state depends upon whether or not the floating gate is charged or uncharged. When electrons are present on the floating gate, the bit state is 0. When electrons are removed from the floating gate, the bit state is 1.
The process by which data is written to NAND flash memory is called tunnel injection.