NAND

NAND flash is nonvolatile memory with multiple floating gates or charge-trapping transistors. Several transistors are connected, and the binary value is controlled by bit line and word line. NAND flash has been migrated from a 2D to a 3D structure to meet the requirement for high bit density. NAND flash can have several bits per cell, which add greater density but with drawbacks in endurance and/or performance:

• SLC: Single-level cell
• MLC: Multilevel cell (2 bits per cell)
• TLC: 3 bits per cell
• QLC: 4 bits per cell