Spherical and well-separated tungsten nanocrystals embedded in the SiO2 layer are demonstrated for the low-voltage nonvolatile memory device. The tungsten dots are formed, based on the thermal oxidation of the tungsten silicide, with a mean size and aerial density of 4.5 nm and 3.7 x 10(11)/ cm(2), 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 106 write/erase cycles. (C) 2005 The Electrochemical Society.