Electron charging and discharging effects of tungsten nanocrystals embedded in silicon dioxide for low-voltage nonvolatile memory technology

Spherical and well-separated tungsten nanocrystals embedded in the SiO ₂ layer are demonstrated for the low-voltage nonvolatile memory device. The tungsten dots are formed, based on the thermal oxidation of the tungsten suicide, with a mean size and aerial density of 4.5 nm and 3.7 × 10¹¹/cm², respectively. A pronounced capacitance-voltage hysteresis is observed with a memory window of 0.95 V under the 3 V programming voltage. Also, the endurance of the memory device is not degraded up to 10 ⁶ write/erase cycles.