Tungsten oxide/tungsten nanocrystals for nonvolatile memory devices

In this work, the fabrication of WO3∕W nanocrystals for nonvolatile memory devices has been achieved via rapid thermal oxidation of tungsten silicide. Amorphous Si and WSix (x=2.7) layers were deposited onto the tunneling oxide and sequentially oxidized to form well-shaped WO3∕W nanocrystals. The mean size of WO3∕W nanocrystals is ∼8.4nm, while density is ∼1.57×1011cm−2. Moreover, the nonvolatile memory device for WO3∕W nanocrystals exhibits ∼0.53V threshold voltage shift under 1V∕(−5V) operation. The sample without capping a-Si layer was also fabricated for comparison. By material analyses, reasonable formation mechanisms are proposed in this letter.