Browsing by Author "Tzeng, Wen-Hsien"

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Bipolar resistive switching effect in Gd(2)O(3) films for transparent memory application
(2011-07-01)
Liu, Kou-Chen
;
Tzeng, Wen-Hsien
;
Chang, Kow-Ming
;
Chan, Yi-Chun
;
Kuo, Chun-Chih
A transparent resistive random access memory based on ITO/Gd(2)O(3)/ITO capacitor structure is fabricated on glass substrate. The transparent memory exhibits reliable resistive switching for more than 1000 cycles, low operation voltage of -2 V/+2 V, and highly transmittance above 80% for visible light. From the TEM and XPS analysis, the asymmetry of the interfacial layer thickness is responsible for the asymmetric switching properties. The transitional multi-valance states of the bottom interfacial layer can serve as oxygen reservoir for oxygen migration back and forth under different polarity of applied bias. This work presents a candidate material Gd(2)O(3) for the application on the T-RRAM devices. (C) 2011 Elsevier B.V. All rights reserved.
Bipolar resistive switching effect in Gd2O3 films for transparent memory application
(2011-07-01)
Liu, Kou-Chen
;
Tzeng, Wen-Hsien
;
Chang, Kow-Ming
;
Chan, Yi-Chun
;
Kuo, Chun-Chih
A transparent resistive random access memory based on ITO/Gd2O3/ITO capacitor structure is fabricated on glass substrate. The transparent memory exhibits reliable resistive switching for more than 1000 cycles, low operation voltage of -2 V/+2 V, and highly transmittance above 80% for visible light. From the TEM and XPS analysis, the asymmetry of the interfacial layer thickness is responsible for the asymmetric switching properties. The transitional multi-valance states of the bottom interfacial layer can serve as oxygen reservoir for oxygen migration back and forth under different polarity of applied bias. This work presents a candidate material Gd2O3 for the application on the T-RRAM devices. (C) 2011 Elsevier B.V. All rights reserved.
Effect of ITO electrode with different oxygen contents on the electrical characteristics of HfOx RRAM devices
(2013-09-01)
Zhong, Chia-Wen
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Tzeng, Wen-Hsien
;
Liu, Kou-Chen
;
Lin, Horng-Chih
;
Chang, Kow-Ming
In this study, the influence of indium tin oxide (ITO) top electrodes with different oxygen contents on the resistive switching characteristics of HfOx/TiN capacitor structure is investigated. Switching parameters, including set and reset voltage values, and high and low resistance values are highly related to the properties of ITO thin films. Higher resistance values in both states can be obtained when ITO thin films with higher oxygen contents are used as top electrodes; such values are accompanied by larger set voltages and fluctuating transient currents during the reset process. Based on the proposed filament model, we suggest that the switching mechanism of HfOx/TiN structure is attributed to the formation and rupture of conducting filamentary paths near the anodic side, which is highly correlated with the properties of the top electrode. The top electrode must be well determined to obtain reliable switching properties. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.
Effect of ultraviolet light exposure on a HfO(x) RRAM device
(2010-10-01)
Liu, Kou-Chen
;
Tzeng, Wen-Hsien
;
Chang, Kow-Ming
;
Chan, Yi-Chun
;
Kuo, Chun-Chih
This paper studies the effect of ultraviolet (UV) light exposure on the resistive switching characteristics of an ITO/HfO(x)/TiN structure. Unstable and unreliable switching properties are generally observed on the ITO/HfO(x)/TiN sample. Under the appropriate exposure time, the samples were able to achieve the superior electrical characteristics and reduced resistance dispersion. We suggest that the improvement of switching characteristics and resistance dispersion is related to the oxygen-rich HfO(2) layer formed at the M/O interface caused by UV light. This indicates that UV laser exposure is a critical issue in the electrical characteristics of RRAM devices. (C) 2010 Elsevier B.V. All rights reserved.
Effect of ultraviolet light exposure on a HfOx RRAM device
(2010-10-01)
Liu, Kou-Chen
;
Tzeng, Wen-Hsien
;
Chang, Kow-Ming
;
Chan, Yi-Chun
;
Kuo, Chun-Chih
This paper studies the effect of ultraviolet (UV) light exposure on the resistive switching characteristics of an ITO/HfOx/TiN structure. Unstable and unreliable switching properties are generally observed on the ITO/HfOx/TiN sample. Under the appropriate exposure time, the samples were able to achieve the superior electrical characteristics and reduced resistance dispersion. We suggest that the improvement of switching characteristics and resistance dispersion is related to the oxygen-rich HfO2 layer formed at the M/O interface caused by UV light. This indicates that UV laser exposure is a critical issue in the electrical characteristics of RRAM devices. (C) 2010 Elsevier B.V. All rights reserved.
Higher Drive Current for SiGe Nanowires
(2008)
Chang, Kow-Ming
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Kuo, Jiun-Ming
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Wu, Heng-Hsin
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Tzeng, Wen-Hsien
;
Wu, Tzu-liu
Nanowire is mainly used in biological sensor because it has the high surface-to-volume ratio. In this study, we have successfully fabricated the Poly-Si and SiGe nanowire with Ge = 7% and 11 % respectively by side-wall spacer technique. In order to normalize the drive current of nanowires, we consider the nanowire as a resistance. The conductance Is chose for comparison between the nanowires. The higher conductance achieved of SlGe nanowire with/without nanowire implantation and the SlGe nanowire with higher Ge concentration had higher conductance. However, the disadvantage of lower contact resistance Is found in SiGe pad. The 3-amino-propyltriethoxy-silane (APTES) was used to modify the surface, which can detect the charge with different pH. Comparing the conductance change; the SiGe nanowire with higher Ge concentration improved the sensitivity. But the over-higher Ge concentration (40%) did not Increase the sensitivity; the reason maybe the higher defect appears at the surface as higher Ge concentration.
Investigation of the effect of different oxygen partial pressure to LaAlO3 thin film properties and resistive switching characteristics
(2011-12-01)
Liu, Kou-Chen
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Tzeng, Wen-Hsien
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Chang, Kow-Ming
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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.
Investigation on the abnormal resistive switching induced by ultraviolet light exposure based on HfOx film
(2010-12-01)
Chang, Kow-Ming
;
Tzeng, Wen-Hsien
;
Liu, Kou-Chen
;
Chan, Yi-Chun
;
Kuo, Chun-Chih
Effect of ultraviolet (UV) light exposure on the resistive switching characteristics of a ITO/HfOx/TiN structure were investigated in this study. Samples exposed with and without ITO shield film exhibit distinct switching characteristics, including leakage current, I-V curves, set and reset voltage fluctuation. Based on random circuit network simulation by Liu et al., we suggest the distinction was attributed to the different filament shapes during forming process. Defects preexisted inside the HfOx film can cause large difference on the electrical properties. Therefore, the UV laser exposure is a critical issue on the electrical characteristics of RRAM devices. (C) Elsevier Ltd. All rights reserved.
Resistance Switching in Ni/HfOx/Ni Nonvolatile Memory Device with CF4/O-2 Plasma Post-treatment
(2012-01-01)
Lai, Chiung-Hui
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Chang, Te-Shun
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Tzeng, Wen-Hsien
;
Chang, Kow-Ming
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電子工程學系及電子研究所
The resistance switching characteristics of Ni/HfOx/Ni capacitor structures with CF4/O-2 plasma post-treatment of different gas flow rate ratios were investigated. The HfOx film was deposited by an electron-gun evaporator, followed by the CF4/O-2 plasma post-treatment with different gas flow rate ratios. According to the filament model, conducting filaments (CFs) are formed by the percolation of various types of defects such as oxygen ions and oxygen vacancies. Moreover, the incorporation of oxygen/fluorine may terminate the oxygen vacancies to form Hf-F bonds and eliminate both fixed and interface traps, which can help to form fixed CFs in the film owing to local stronger Hf-F bonds. In this work, the improvement in the stability of resistance switching and current in the high-resistance state (HRS) was achieved by suitable plasma post-treatment. This may be attributed to the formation of Hf-F bonds as observed through electron spectroscopy for chemical analysis. (C) 2012 The Japan Society of Applied Physics
Resistive switching characteristics of multilayered (HfO2/Al2O3)(n) n=19 thin film
(2012-02-01)
Tzeng, Wen-Hsien
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Zhong, Chia-Wen
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Liu, Kou-Chen
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Chang, Kow-Ming
;
Lin, Horng-Chih
A transparent resistive random access memory used as Indium Tin Oxide (ITO) electrode, ITO/HfO2/Al2O3/center dot center dot center dot/HfO2/Al2O3/ITO capacitor structure is fabricated on glass substrate by atomic layer deposition. The unipolar resistive switching characteristics can be performed by applying the positive- or negative-bias through top electrode, however, the differences of switching and stability in the two different operations can be observed. The diversities of electrical property are attributed to different oxide/ITO interface materials, which influence the current flow of the injected electrons. Crown Copyright (c) 2011 Published by Elsevier B.V. All rights reserved.
The effect of plasma deposition on the electrical characteristics of Pt/HfO(x)/TiN RRAM device
(2010-12-25)
Liu, Kou-Chen
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Tzeng, Wen-Hsien
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Chang, Kow-Ming
;
Wu, Chi-Hung
;
電子工程學系及電子研究所
The electrical characteristics affected by plasma ions during resistive switching are investigated on an HfO(x)/TiN RRAM capacitor device. Experimental fabrications of the Pt electrode by e-beam evaporation, dc sputtering and stacked Pt electrode (evaporated first followed by sputtered deposition) are presented for discussion. The samples exhibit distinct electrical characteristics both under voltage- and current-mode measurement. The sputtered sample clearly demonstrates large-scale dispersion on high resistance values caused by sputtered ionized particle (Ar(+)) damage from the voltage-mode operation. Furthermore, intermediate resistance states and anomalous switching during high- to low-state switching by current-mode indicates that the unstable conducting filamentary paths are randomly formed. This result differs completely from that of the evaporated sample. On the stacked Pt electrode, an evaporated thin Pt layer inserted before sputtering deposition effectively reduces resistance dispersion. The external plasma damage gives clues that unreliable and unstable resistive switching characteristics can result from the sputtered damage during top electrode deposition. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.
The effect of plasma deposition on the electrical characteristics of Pt/HfOx/TiN RRAM device
(2010-12-25)
Liu, Kou-Chen
;
Tzeng, Wen-Hsien
;
Chang, Kow-Ming
;
Wu, Chi-Hung
;
電子工程學系及電子研究所
The electrical characteristics affected by plasma ions during resistive switching are investigated on an HfOx/TiN RRAM capacitor device. Experimental fabrications of the Pt electrode by e-beam evaporation, dc sputtering and stacked Pt electrode (evaporated first followed by sputtered deposition) are presented for discussion. The samples exhibit distinct electrical characteristics both under voltage- and current-mode measurement. The sputtered sample clearly demonstrates large-scale dispersion on high resistance values caused by sputtered ionized particle (Ar+) damage from the voltage-mode operation. Furthermore, intermediate resistance states and anomalous switching during high- to low-state switching by current-mode indicates that the unstable conducting filamentary paths are randomly formed. This result differs completely from that of the evaporated sample. On the stacked Pt electrode, an evaporated thin Pt layer inserted before sputtering deposition effectively reduces resistance dispersion. The external plasma damage gives clues that unreliable and unstable resistive switching characteristics can result from the sputtered damage during top electrode deposition. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.
The Ge Enhance the Sensitivity for Bio-Sensor
(2008)
Chang, Kow-Ming
;
Kuo, Jiun-Ming
;
Chao, Wen-Chan
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Liang, Chia-Jung
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Wu, Heng-Hsin
Nanowire is mainly used in biological sensor because it has the high surface-to-volume ratio. In this study, we have successfully fabricated the N-SiGe nanowire with different Ge concentration by side-wall spacer technique respectively. The 3-amino-propyltrime-thoxy-silane (APTS) was used to modify the surface, which can connect the bio-linker. The conductance of SiGe nanowire Increases owing to APTS with positive charge. The his (sulfosuccinimidyl) suberate sodium (BS3) as the bio-linker connects to APTS, and the conductance decreases because of negative charge. Finally, the protein immunoglobulin G (IGG) is linked to BS3, and the conductance reduces for negative charge. Comparing the conductance change; the SiGe nanowire with higher Ge concentration improved the sensitivity. But the over-higher Ge concentration (40%) did not increase the sensitivity; the reason maybe the higher defect appears at the surface as higher Ge concentration.
The resistive switching characteristics of a Ti/Gd(2)O(3)/Pt RRAM device
(2010-05-01)
Liu, Kou-Chen
;
Tzeng, Wen-Hsien
;
Chang, Kow-Ming
;
Chan, Yi-Chun
;
Kuo, Chun-Chih
We successfully fabricated the Gd(2)O(3) film for the application of resistive random access memory (RRAM). The resistive switching behavior of the Ti/Gd(2)O(3)/Pt capacitor structure could be both operated under positive or negative bias. However, there was a significant difference on the switching properties. The switching behavior under positive bias operation was more stable, had less voltage and resistance fluctuation, and had longer endurance than that of the negative one. We propose that the anode electrode plays an important role in the switching characteristics and may be the cause of the asymmetry of the I-V curves between positive and negative operation. (C) 2010 Elsevier Ltd. All rights reserved.
The resistive switching characteristics of a Ti/Gd2O3/Pt RRAM device
(2010-05-01)
Liu, Kou-Chen
;
Tzeng, Wen-Hsien
;
Chang, Kow-Ming
;
Chan, Yi-Chun
;
Kuo, Chun-Chih
We successfully fabricated the Gd2O3 film for the application of resistive random access memory (RRAM). The resistive switching behavior of the Ti/Gd2O3/Pt capacitor structure could be both operated under positive or negative bias. However, there was a significant difference on the switching properties. The switching behavior under positive bias operation was more stable, had less voltage and resistance fluctuation, and had longer endurance than that of the negative one. We propose that the anode electrode plays an important role in the switching characteristics and may be the cause of the asymmetry of the I-V curves between positive and negative operation. (C) 2010 Elsevier Ltd. All rights reserved.
Transparent resistive random access memory (T-RRAM) based on Gd2O3 film and its resistive switching characteristics
(2010)
Liu, Kou-Chen
;
Tzeng, Wen-Hsien
;
Chang, Kow-Ming
;
Chan, Yi-Chun
;
Kuo, Chun-Chih
A transparent resistive random access memory (T-RRAM) based on ITO/Gd2O3/ITO capacitor structure is successfully fabricated on Glass substrate by pulse laser deposition (PLD) at room temperature. Under bipolar operation, the ITO/Gd2O3/ITO device exhibits reliable and stable resistive switching behaviors for more than 200 switching cycles and low operation voltage of -2V/+2V. Furthermore, our device demonstrates nonpolar resistive switching characteristic which exhibits high potential to be applied for the next generation nonvolatile memory.