Browsing by Author "Lee, Yun-Ju"

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Intensify the application of ZnO-based nanodevices in humid environment: O-2/H-2 plasma suppressed the spontaneous reaction of amorphous ZnO nanowires
(2014-06-02)
Lai, Chun-Yen
;
Chien, Tzu-Chiao
;
Lin, Ting-Yi
;
Ke, Teng
;
Hsu, Shih-Han
In this work, we have demonstrated that amorphous ZnO nanobranches (a-ZnO NBs) could spontaneously react from the crystalline ZnO NWs (c-ZnO NWs) at specific humid environment. The spontaneous reaction mechanism and result can be analyzed by humidity controlling and optical microscope (OM)/scanning electron microscope (SEM)/Kelvin probe force microscopy (KPFM)/transmission electron microscopy (TEM) system. We can make the c-ZnO NWs spontaneous reaction happen at different humid environments and suppress the a-ZnO NBs spontaneous reaction by oxygen/hydrogen plasma surface passivation. The hydrogen plasma surface treatment also can improve the UV sensing sensitivity more than twofold. This work provides the mechanism and methods of the a-ZnO NBs spontaneous growth and offers the passivation treatment for strengthening and enhancing ZnO-based nanodevice application in humid environment and UV light detection, respectively.
Investigation of the effect of different oxygen partial pressure to LaAlO3 thin film properties and resistive switching characteristics
(2011-12-01)
Liu, Kou-Chen
;
Tzeng, Wen-Hsien
;
Chang, Kow-Ming
;
Huang, Jiun-Jie
;
Lee, Yun-Ju
The pulsed laser deposition and growth of a high-k dielectric lanthanum aluminate LaAlO3 (LAO) thin film on indium tin oxide/glass substrate at different oxygen partial pressure was studied. Based on the pulsed laser deposition growth mechanism, we explain how a difference in the oxygen partial pressure influences the surface roughness, formation of an interfacial layer, and the transparent resistive switching characteristics of LAO thin films. The micro-structure and oxygen concentration difference inside LAO thin films may be the main reason for the difference in electrical and resistive switching properties. Films grown at higher oxygen partial pressure displayed more reliable resistive switching performance, due to the formation of the interfacial layer and a lower concentration of oxygen vacancies. The interfacial layer serves as a good oxygen reservoir and the involvement of more oxygen ions ensures the switching reliability. The migration of oxygen ions between the interfacial layer and the LAO film under applied bias may be the switching mechanism. (C) 2011 Elsevier B. V. All rights reserved.
The Static Standing Postural Stability Measured by Average Entropy
(2019-12-01)
Wei, Sung-Yang
;
Hsu, Chang Francis
;
Lee, Yun-Ju
;
Hsu, Long
;
Chi, Sien
Static standing postural stability has been measured by multiscale entropy (MSE), which is used to measure complexity. In this study, we used the average entropy (AE) to measure the static standing postural stability, as AE is a good measure of disorder. The center of pressure (COP) trajectories were collected from 11 subjects under four kinds of balance conditions, from stable to unstable: bipedal with open eyes, bipedal with closed eyes, unipedal with open eyes, and unipedal with closed eyes. The AE, entropy of entropy (EoE), and MSE methods were used to analyze these COP data, and EoE was found to be a good measure of complexity. The AE of the 11 subjects sequentially increased by 100% as the balance conditions progressed from stable to unstable, but the results of EoE and MSE did not follow this trend. Therefore, AE, rather than EoE or MSE, is a good measure of static standing postural stability. Furthermore, the comparison of EoE and AE plots exhibited an inverted U curve, which is another example of a complexity versus disorder inverted U curve.