Browsing by Author "Liu, Kou-Chen"

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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
;
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.
Impact of gate dielectrics and oxygen annealing on tin-oxide thin-film transistors
(2016-04)
Zhong, Chia-Wen
;
Lin, Horng-Chih
;
Tsai, Jung-Ruey
;
Liu, Kou-Chen
;
Huang, Tiao-Yuan
In this work, we study the impact of gate dielectrics on the characteristics of bottom-gated tin-oxide thin-film transistors annealed in an oxygen ambience at 300 degrees C for various periods. SiO2, HfO2, and Al2O3 are employed as the gate dielectric in the test devices. The results show that the devices will start exhibiting p-type conduction behavior as the annealing reaches a specific time period which is closely related to the underlying gate dielectric, and the device characteristics can be improved as the annealing proceeds further. Nonetheless, a prolonged annealing may cause degradation of the devices. High hole mobility (3.33 cm(2)V(-1)s(-1)), low threshold voltage (1.95 V), and excellent I-on/I-off ratio (similar to 10(4)) are achieved on SnO TFTs with a SiO2 gate dielectric after an annealing of 30 min. (C) 2016 The Japan Society of Applied Physics
Impact of gate dielectrics and oxygen annealing on tin-oxide thin-film transistors
(2016-04-01)
Zhong, Chia-Wen
;
Lin, Horng-Chih
;
Tsai, Jung-Ruey
;
Liu, Kou-Chen
;
Huang, Tiao-Yuan
In this work, we study the impact of gate dielectrics on the characteristics of bottom-gated tin-oxide thin-film transistors annealed in an oxygen ambience at 300 degrees C for various periods. SiO2, HfO2, and Al2O3 are employed as the gate dielectric in the test devices. The results show that the devices will start exhibiting p-type conduction behavior as the annealing reaches a specific time period which is closely related to the underlying gate dielectric, and the device characteristics can be improved as the annealing proceeds further. Nonetheless, a prolonged annealing may cause degradation of the devices. High hole mobility (3.33 cm(2)V(-1)s(-1)), low threshold voltage (1.95 V), and excellent I-on/I-off ratio (similar to 10(4)) are achieved on SnO TFTs with a SiO2 gate dielectric after an annealing of 30 min. (C) 2016 The Japan Society of Applied Physics
Impact of thermal oxygen annealing on the properties of tin oxide films and characteristics of p-type thin-film transistors
(2016-01-01)
Zhong, Chia-Wen
;
Lin, Horng-Chih
;
Liu, Kou-Chen
;
Huang, Tiao-Yuan
;
電子工程學系及電子研究所
In this work, we study the properties of tin oxide films, which were annealed in oxygen ambient for various periods. The as-deposited tin oxides are tin-dominant and, from the Hall measurements, they are of the n-type with high electron concentrations (>10(19) cm(-3)) and would change to the p-type when the oxygen annealing is sufficiently long. We have also found that changes in the structure and crystallinity of the channel layer can be clearly observed by X-ray diffraction analysis and optical microscopy. On the basis of the observations, a physical scheme is proposed to describe the evolution of the electrical performance of oxygen-annealed devices. A hole mobility of 3.24 cm(2) V-1 s(-1), a subthreshold swing of 0.43V/dec, a threshold voltage of 1.4V, and an on/off current ratio larger than 10(3) are obtained as the channel is transformed into SnO. (C) 2016 The Japan Society of Applied Physics
Impact of thermal oxygen annealing on the properties of tin oxide films and characteristics of p-type thin-film transistors
(2016-01)
Zhong, Chia-Wen
;
Lin, Horng-Chih
;
Liu, Kou-Chen
;
Huang, Tiao-Yuan
;
電子工程學系及電子研究所
In this work, we study the properties of tin oxide films, which were annealed in oxygen ambient for various periods. The as-deposited tin oxides are tin-dominant and, from the Hall measurements, they are of the n-type with high electron concentrations (>10(19) cm(-3)) and would change to the p-type when the oxygen annealing is sufficiently long. We have also found that changes in the structure and crystallinity of the channel layer can be clearly observed by X-ray diffraction analysis and optical microscopy. On the basis of the observations, a physical scheme is proposed to describe the evolution of the electrical performance of oxygen-annealed devices. A hole mobility of 3.24 cm(2) V-1 s(-1), a subthreshold swing of 0.43V/dec, a threshold voltage of 1.4V, and an on/off current ratio larger than 10(3) are obtained as the channel is transformed into SnO. (C) 2016 The Japan Society of Applied Physics
Improving Electrical Performances of p-Type SnO Thin-Film Transistors Using Double-Gated Structure
(2015-10-01)
Zhong, Chia-Wen
;
Lin, Horng-Chih
;
Liu, Kou-Chen
;
Huang, Tiao-Yuan
;
電子工程學系及電子研究所
p-type SnO thin-film transistors (TFTs) using a nominally symmetrical double-gated (DG) structure were studied in this letter. The top and bottom gates can be biased independently (single-gated mode) or jointly to switch the device (DG mode). For the latter operation, it is shown that ON current, subthreshold swing, and OFF-state current of the SnO TFT are all improved as compared with the operations when only one of the two gates is biased. As the device is operated under the DG mode, field-effect mobility of 6.54 cm(2)/V-s, high ON/OFF current ratio of >10(5), and subthreshold swing of 143 mV/decade are obtained. Moreover, the capability of the device in tuning its transfer characteristics under the single-gated operation with the bias applied to the opposite gate is also confirmed.
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
;
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.
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.
Resistive switching characteristics of multilayered (HfO2/Al2O3)(n) n=19 thin film
(2012-02-01)
Tzeng, Wen-Hsien
;
Zhong, Chia-Wen
;
Liu, Kou-Chen
;
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.
Role of Depolarization Factors in the Evolution of a Dipolar Plasmonic Spectral Line in the Far- and Near-Field Regimes
(2020-02-06)
Januar, Mochamad
;
Liu, Bei
;
Cheng, Jui-Ching
;
Hatanaka, Koji
;
Misawa, Hiroaki
In this article, the excitation of dipolar localized surface plasmon resonances (LSPRs) in both the far- and near-field regions is described in terms of the relevant static, dynamic, and radiative depolarization factors. This approach offers a direct relationship between the evolution of the LSPR spectral line and the depolarization components in an analogous sense to a harmonic oscillator. The static, dynamic, and radiative terms reflect the coefficients of the "stiffness", effective mass, and damping in the oscillator system, respectively. Hence, one can immediately perceive that the static part of the depolarization factor is mainly responsible for the shifts in the resonant frequency, and the radiative part is responsible for the change in bandwidth. Additionally, the dynamic part behaves like an effective mass, acting as an inertial weighting factor that decides how significant the changes taking place in the system are. From this model, we can rationalize that the qualitative behavior of the far-field efficiency primarily depends on the shifting resonant frequencies, and the corresponding near-field efficiency is highly sensitive to the presence of damping. The model also clarifies the discrepancy in the resonant frequency and bandwidth between the far- and near-field spectra, which is due to the significant presence of the radiative component. These basic descriptions can be used as a guiding principle for handling more sophisticated structures and gaining more rationalized designs for novel applications related to the LSPR mechanism.
Room temperature epitaxial growth of (001) CeO2 on (001) LaAlO3 by pulsed laser deposition
(2013-05-01)
Ho, Yen-Teng
;
Chang, Kuo-Shu
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Liu, Kou-Chen
;
Hsieh, Li-Zen
;
Liang, Mei-Hui
The room temperature epitaxial growth of CeO2 on lattice matched (001) LaAlO3 substrates by using pulsed laser deposition (PLD) method under various oxygen partial pressure (Po-2) is demonstrated. X-ray diffraction analysis with 2-Theta/rocking curve/Phi-scan, cross-sectional transmission electron microscopy with selected-area diffractions are used to characterize structural of grown films. The epitaxial (001) CeO2 can be achieved at room temperature under Po-2 less than 2 x 10(-3) Torr. The best quality of grown film is obtained under Po-2 = 2 x 10(-5) Torr and degraded under Po-2 = 2 x 10(-6) Torr due to oxygen deficiency in structure. The epitaxial relationship between CeO2 and LAO is confirmed to be (001)CeO2 //(001)LAO, [100](CeO2)//[110](LAO) and [010](CeO2)//[(1)over-bar10](LAO). No obvious reduction reaction occurred, from Ce+4 turned into Ce+3 states, as reducing oxygen partial pressure during growth by PLD.
The effect of plasma deposition on the electrical characteristics of Pt/HfO(x)/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 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 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.