Browsing by Author "Chen, U. S."

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Nickel nanocrystals with HfO2 blocking oxide for nonvolatile memory application
(2007-05-28)
Yang, F. M.
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Chang, T. C.
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Liu, P. T.
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Chen, U. S.
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Yeh, P. H.
A distributed charge storage with Ni nanocrystals embedded in the SiO2 and HfO2 layer has been fabricated in this study. The mean size and aerial density of the Ni nanocrystals are estimated to be about 5 nm and 3.9x10(12)/cm(2), respectively. The nonvolatile memory device with Ni nanocrystals exhibits 1 V threshold voltage shift under 4 V write operation. The device has a long retention time with a small charge lose rate. Besides, the endurance of the memory device is not degraded up to 10(6) write/erase cycles. (C) 2007 American Institute of Physics.
Tungsten nanocrystal memory devices improved by supercritical fluid treatment
(2007-12-03)
Chen, C. H.
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Chang, T. C.
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Liao, I. H.
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Xi, P. B.
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Tsai, C. T.
A supercritical CO(2) (SCCO(2)) fluid technique is proposed to improve electrical characteristics for W nanocrystal nonvolatile memory devices, since the thickness and quality of tunnel oxide are critical issues for the fabrication of nonvolatile memory devices. After SCCO(2) treatments, C-V curves are restored to normal, as well as the leakage current of W nanocrystal memory devices are reduced significantly. It reveals that W nanocrystal memory devices could be formed with shorter oxidation time, moreover, dangling bonds and trapping states initially created within an incomplete oxidized film will be efficiently repaired after SCCO(2) treatment. (c) 2007 American Institute of Physics.
Tungsten oxide/tungsten nanocrystals for nonvolatile memory devices
(2008-01-07)
Chen, C. H.
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Chang, T. C.
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Liao, I. H.
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Xi, P. B.
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Hsieh, Joe
In this work, the fabrication of WO(3)/W nanocrystals for nonvolatile memory devices has been achieved via rapid thermal oxidation of tungsten silicide. Amorphous Si and WSi(x) (x=2.7) layers were deposited onto the tunneling oxide and sequentially oxidized to form well-shaped WO(3)/W nanocrystals. The mean size of WO(3)/W nanocrystals is similar to 8.4 nm, while density is similar to 1.57x10(11) cm(-2). Moreover, the nonvolatile memory device for WO(3)/W nanocrystals exhibits similar to 0.53 V threshold voltage shift under 1 V/(-5 V) operation. The sample without capping a-Si layer was also fabricated for comparison. By material analyses, reasonable formation mechanisms are proposed in this letter. (C) 2008 American Institute of Physics.
Using double layer CoSi2 nanocrystals to improve the memory effects of nonvolatile memory devices
(2007-05-21)
Yang, F. M.
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Chang, T. C.
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Liu, P. T.
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Yeh, P. H.
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Chen, U. S.
The nonvolatile memory device with multilayer nanocrystals has advantages such as the memory effects can be increased by the increasing density of the nanocrystals and the whole retention characteristic can be improved. There are much more electrons that can be stored in the double layer than single layer nanocrystal memory device. The double layer CoSi2 nanocrystals have better retention characteristic than the single layer. The good retention characteristic of the double layer device is due to the Coulomb-blockage effects on the top layer nanocrystals from the bottom layer nanocrystals. So, the memory effects of the nonvolatile memory device can be improved by using the double layer nanocrystals. (c) 2007 American Institute of Physics.