Browsing by Author "Ho, New-Jin"

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Formation and composition of titanium oxinitride nanocrystals synthesized via nitridizing titanium oxide for nonvolatile memory applications
(2011-09-01)
Feng, Li-Wei
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Chang, Chun-Yen
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Chang, Ting-Chang
;
Tu, Chun-Hao
;
Wang, Pai-Syuan
Formation and composition analyses of titanium oxinitride nanocrystals (NCs) fabricated via treating a magnetron co-sputtered thin film of titanium and silicon dioxide with a rapid thermal annealing in nitrogen ambient were demonstrated for nonvolatile memory applications. Phase separation characteristics with different annealing conditions were examined by transmission electron microscopy and chemical bonding characteristics were confirmed by X-ray photon emission spectra. It was observed that a blanket layer composed mainly of titanium oxide was still present as annealing temperature was increased to 700 degrees C, associated with the thermodynamically stable phase of titanium oxide. Furthermore, a higher thermal treatment of 900 degrees C induced formation of a well-separated NC structure and caused simultaneously partial nitridation of the titanium oxide, thereby forming titanium oxinitride NCs. A significant capacitance-voltage hysteresis in threshold voltage shift at 1 V was easily achieved under a small sweeping voltage range of + 2 V/-2 V, and a memory window retention of 2.2 V was obtained after 10(7) s by extrapolation under a 1 s initial-program/erase condition of +5 V/-5 V, respectively. (C) 2011 Elsevier B.V. All rights reserved.
Improvement of the performance of ZnO TFTs by low-temperature supercritical fluid technology treatment
(2009-12-25)
Chen, Min-Chen
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Chang, Ting-Chang
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Huang, Sheng-Yao
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Chang, Kuan-Chang
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Huang, Hui-Chun
in this paper, the supercritical CO(2) (SCCO(2)) fluid technology is successfully applied to improve the electrical characteristics of sputtered ZnO TFTs at low temperature (150 degrees C). After the treatment of SCCO(2) fluids mixed with water, the ZnO TFT exhibited superior transfer characteristics and lower threshold voltage. According to X-ray photoelectron spectroscopy (XPS) analyses, the improvements were attributed to the increase of binding energies of Zn-O bonds, hydrogen-related donors and the reduction of traps at the grain boundaries in ZnO thin films. In addition, the crystalline quality and microstructure of ZnO thin films were also investigated by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The transmittance of the ZnO film was measured by an N&K analyzer 1280 (N&K Technology, Inc.), which is a new type of thin-film measurement system. (C) 2009 Elsevier B.V. All rights reserved.
Low temperature synthesis and electrical characterization of germanium doped Ti-based nanocrystals for nonvolatile memory
(2011-11-30)
Feng, Li-Wei
;
Chang, Chun-Yen
;
Chang, Ting-Chang
;
Tu, Chun-Hao
;
Wang, Pai-Syuan
Chemical and electrical characteristics of Ti-based nanocrystals containing germanium, fabricated by annealing the co-sputtered thin film with titanium silicide and germanium targets, were demonstrated for low temperature applications of nonvolatile memory. Formation and composition characteristics of nanocrystals (NCs) at various annealing temperatures were examined by transmission electron microscopy and X-ray photon-emission spectroscopy, respectively. It was observed that the addition of germanium (Ge) significantly reduces the proposed thermal budget necessary for Ti-based NC formation due to the rise of morphological instability and agglomeration properties during annealing. NC structures formed after annealing at 500 degrees C, and separated well at 600 degrees C annealing. However, it was also observed that significant thermal desorption of Ge atoms occurs at 600 degrees C due to the sublimation of formatted GeO phase and results in a serious decrease of memory window. Therefore, an approach to effectively restrain Ge thermal desorption is proposed by encapsulating the Ti-based trapping layer with a thick silicon oxide layer before 600 degrees C annealing. The electrical characteristics of data retention in the sample with the 600 degrees C annealing exhibited better performance than the 500 C-annealed sample, a result associated with the better separation and better crystallization of the NC structures. (C) 2011 Elsevier B.V. All rights reserved.
Resistive switching characteristics of ytterbium oxide thin film for nonvolatile memory application
(2011-12-30)
Tseng, Hsueh-Chih
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Chang, Ting-Chang
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Huang, Jheng-Jie
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Chen, Yu-Ting
;
Yang, Po-Chun
This paper studies the effects of both the positive and negative forming processes on the resistive switching characteristics of a Pt/Yb(2)O(3)/TiN RRAM device. The polarity of the forming process can determine the transition mechanism, either bipolar or unipolar. Bipolar behavior exists after the positive forming process, while unipolar behavior exists after the negative forming process. Furthermore, the bipolar switching characteristics of the Pt/Yb(2)O(3)/TiN device can be affected by using a reverse polarity forming treatment, which not only reduces the set and reset voltage, but also improves the on/off ratio. Crown Copyright (C) 2011 Published by Elsevier B. V. All rights reserved.