Browsing by Author "Chang, Kuan-Chang"

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A low-temperature method for improving the performance of sputter-deposited ZnO thin-film transistors with supercritical fluid
(2009-04-20)
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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Li, Hung-Wei
A low-temperature method, supercritical CO(2) (SCCO(2)) fluid technology, is employed to improve the device properties of ZnO TFT at 150 degrees C. In this work, the undoped ZnO films were deposited by sputter at room temperature and treated by SCCO(2) fluid which is mixed with 5 ml pure H(2)O. After SCCO(2) treatment, the on/off current ratios and threshold voltage of the device were improved significantly. From x-ray photoelectron spectroscopy analyses, the enhancements were attributed to the stronger Zn-O bonds, the hydrogen-related donors, and the reduction in dangling bonds at the grain boundary by OH passivation.
A Universal Model for Interface-type Threshold Switching Phenomena by Comprehensive Study of Vanadium Oxide-Based Selector
(2017-01-01)
Lin, Chih-Yang
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Chen, Ying-Chen
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Gu, Meiqi
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Pan, Chih-Hung
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Jin, Fu-Yuan
For the first time, a comprehensive study of Vanadium oxide-based selector characteristics with a universal model observed by thermal and electrical induced threshold switching (TS) phenomena at interface is presented in this work. The model can explain that the resistance evolution by thermal temperature in TS behaviors, as well as the resistance gradually increases with cycling ("seasoning effect"). Compatible current density (10(7)similar to 10(9) A/cm(2)) and selectivity (similar to 100) with physical understanding of evolution in energy barrier and MIT metallic state modulation are studied. The results show a promising design guideline for future storage-class memory (SCM) applications.
Abnormal Subthreshold Leakage Current at High Temperature in InGaZnO Thin-Film Transistors
(2012-04-01)
Chang, Geng-Wei
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Chang, Ting-Chang
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Jhu, Jhe-Ciou
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Tsai, Tsung-Ming
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Syu, Yong-En
Abnormal subthreshold leakage current is observed at high temperature in amorphous InGaZnO thin-film transistors. The transfer curve exhibits an apparent subthreshold current stretch-out phenomenon that becomes more serious with increasing temperatures. The negative bias temperature instability experiment has been used to prove high-temperature-induced hole generation. Furthermore, the transfer characteristics with different drain voltages have been also used to confirm the status of hole accumulation. These pieces of evidence clearly defined the stretch-out phenomenon, which is caused by thermal-induced hole generation and accumulation at the source region that leads to source-side barrier lowering.
Adjustable built-in resistor on oxygen-vacancy-rich electrode-capped resistance random access memory
(2016-10)
Pan, Chih-Hung
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Chang, Kuan-Chang
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Chu, Tian-Jian
In this study, an adjustable built-in resistor was observed on an indium-tin oxide (ITO)-capped resistance random access memory (RRAM) device, which has the potential to reduce operating power. Quite notably, the high-resistance state (HRS) current of the device decreased with decreasing current compliance, and a special situation, that is, a gradual change in current always appears and climbs slowly to reach the compliance current in the set process even when the compliance current decreases, was observed. Owing to this observed phenomenon, the device is regarded to be equipped with an adjustable built-in resistor, which has the potential for low-power device application. (C) 2016 The Japan Society of Applied Physics
An Electronic Synapse Device Based on Solid Electrolyte Resistive Random Access Memory
(2015-08-01)
Zhang, Wei
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Hu, Ying
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Chang, Ting-Chang
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Chang, Kuan-Chang
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Tsai, Tsung-Ming
The multilevel capability of solid electrolyte resistive random access memory (RRAM) with a Pt/GeSO/TiN structure was explored for potential use as a synapse device. By varying the cutoff voltage during the dc I-V cycles or the ac pulse programming voltage amplitudes, continuous multilevel conductance states were obtained. The reference Pt/GeO/TiN RRAM was fabricated to certify the multilevel capability and was due to the character of the GeS solid electrolyte. Finally, the property of gradual conductance states was exploited to demonstrate spike-timing-dependent plasticity learning, which suggests device\'s potential for use as an electronic synapse device for neuromorphic systems.
Analysis of Contrasting Degradation Behaviors in Channel and Drift Regions Under Hot Carrier Stress in PDSOI LD N-Channel MOSFETs
(2017-06-01)
Lin, Chien-Yu
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Chang, Ting-Chang
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Liu, Kuan-Ju
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Chen, Li-Hui
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Tsai, Jyun-Yu
This letter studies the effects of hot carrier stress (HCS) in laterally diffused silicon-on-insulator n-channel metal-oxide-semiconductor field-effect transistors. After HCS, threshold voltage and subthreshold swing degrade, while the ON-state current exhibits degradation after an abnormal spike due to hole trapping in the resistprotective oxide. Impact ionization simulation shows that low doping concentrations in the drift region cause a severe Kirk effect under HCS and more severe degradation at higher gate voltages. However, degradation in the channel contrasts with the simulation result, which suggests an additional mechanism. Variable temperature HCS confirms that channel degradation is instead dominated by temperature.
Asymmetric Carrier Conduction Mechanism by Tip Electric Field in WSiOX Resistance Switching Device
(2012-03-01)
Syu, Yong-En
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Chang, Geng-Wei
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Chang, Kuan-Chang
Resistance random access memory (RRAM) is a great potential candidate for next-generation nonvolatile memory due to the outstanding memory characteristic. However, the resistance switching mechanism is still a riddle nowadays. In this letter, the switching mechanism is investigated by current-voltage (I-V) curve fitting in the TiN/WSiOX/Pt RRAM device. The asymmetric phenomenon of the carrier conduction behavior is explained at the high-resistance state in high electric field. The switching behavior is regarded to tip electric field by localizing the filament between the interface of top electrode and insulator.
Atomic-level quantized reaction of HfOx memristor
(2013-04-29)
Syu, Yong-En
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Chang, Ting-Chang
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Lou, Jyun-Hao
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Tsai, Tsung-Ming
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Chang, Kuan-Chang
In this study, we have observed dynamic switching behaviors in a memristive device. There are only a few atoms in the resistive switching reaction which enables the high-speed resistive switching characteristics, which was analyzed dynamically by real-time analyzing tools. From fundamental conductance considerations, the resistance of the conductive path in HfOx memristor is found to be due to barriers which are atomically incremented during the RESET process. Simultaneously, we have demonstrated the quantized switching phenomena at ultra-cryogenic temperature (4 K), which are attributed to the atomic-level reaction in metallic filament. (C) 2013 AIP Publishing LLC.
Attaining resistive switching characteristics and selector properties by varying forming polarities in a single HfO2-based RRAM device with a vanadium electrode
(2017-07-07)
Lin, Chih-Yang
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Chen, Po-Hsun
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Chang, Ting-Chang
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Chang, Kuan-Chang
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Zhang, Sheng-Dong
This study proposes a method for a HfO2-based device to exhibit both resistive switching (RS) characteristics as resistive random access memory (RRAM) and selector characteristics by introducing vanadium (V) as the top electrode. This simple V/HfO2/TiN structure can demonstrate these two different properties depending on forming polarities. The RS mechanism is activated by a positive forming bias. In contrast, the selector property is induced by a negative forming bias. The material analyses firstly confirm the existence of V in the top electrode. Then the electrical measurements for the same V/HfO2/TiN structures but with different forming polarities were carried out to further investigate their DC sweeping characteristics to act as either a selector or RRAM device. Furthermore, reliability tests for both selector and RRAM devices were also conducted to confirm their switching stabilities. Finally, current fitting methods and temperature influence experiments were performed to investigate the carrier transport mechanisms. Finally, physical models were proposed to illustrate the selector property and RS mechanism for selector and RRAM devices, respectively. This simple device structure with its easy operating method accomplishes a significant advancement of devices combining both selector properties and RRAM for remarkable real applications in the near future.
Bipolar Resistive RAM Characteristics Induced by Nickel Incorporated Into Silicon Oxide Dielectrics for IC Applications
(2012-12-01)
Tsai, Tsung-Ming
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Chang, Kuan-Chang
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Chang, Ting-Chang
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Syu, Yong-En
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Chuang, Siang-Lan
In this letter, we successfully produced resistive switching behaviors by nickel doped into silicon oxide at room temperature. The nickel element was doped into silicon oxide, which is a useful dielectric material in integrated circuit (IC) industries by cosputtering technology. Based on the proposed method, satisfactory reliability of the resistance switching device can be demonstrated by endurance and retention evaluation. We believe that the silicon oxide doped with nickel at room temperature is a promising method for resistive random access memory nonvolatile memory applications due to its compatibility with the IC processes.
Characteristics and Mechanisms of Silicon-Oxide-Based Resistance Random Access Memory
(2013-03-01)
Chang, Kuan-Chang
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Tsai, Tsung-Ming
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Chang, Ting-Chang
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Wu, Hsing-Hua
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Chen, Jung-Hui
Traditionally, a large number of silicon oxide materials are extensively used as various dielectrics for semiconductor industries. In general, silicon oxide cannot be used as resistance random access memory (RRAM) due to its insulating electrical properties. In this letter, we have successfully produced resistive switching and forming-free behaviors by zinc doped into silicon oxide. The current-voltage fitting data show that current transport mechanism is governed by Poole-Frenkel behavior in high-resistance state and Ohm's law in low-resistance state, consisting with filament theory. Additionally, good endurance and retention reliabilities are exhibited in the zinc-doped silicon oxide RRAM.
Characteristics of hafnium oxide resistance random access memory with different setting compliance current
(2013-10-14)
Su, Yu-Ting
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Chang, Kuan-Chang
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Zhang, Rui
In this Letter, the characteristics of set process of hafnium oxide based resistance random access memory are investigated by different set processes with increasing compliance current. Through current fitting, carrier conduction mechanism of low resistance state changes from hopping to surface scattering and finally to ohmic conduction with the increase of setting compliance current. Experimental data of current-voltage measurement under successive increasing temperature confirms the conduction mechanism transition. A model of filament growth is eventually proposed in a way by merging discrete metal precipitates and electrical field simulation by COMSOL Multiphysics further clarifies the properties of filament growth process. (C) 2013 AIP Publishing LLC.
Characterization of Oxygen Accumulation in Indium-Tin-Oxide for Resistance Random Access Memory
(2014-06-01)
Zhang, Rui
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Chang, Kuan-Chang
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Huang, Syuan-Yong
In this letter, we report the oxygen accumulation effect and its influence on resistive switching for gadolinium-doped silicon dioxide (Gd:SiO2) resistance random access memory (RRAM). We find that oxygen absorbance by indium-tin-oxide electrode affects the conduction current mechanism, and remarkably modifies the device performance of RRAM devices. By current fitting, Schottky emission can be observed in both low and high resistance states, from which conduction model is proposed to clarify the oxygen accumulation phenomenon. Reliability tests, including endurance and high temperature retention are further carried out, evaluating the significance of oxygen accumulation effect in redox reaction for RRAM devices.
Charge Quantity Influence on Resistance Switching Characteristic During Forming Process
(2013-04-01)
Chu, Tian-Jian
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Wu, Hsing-Hua
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Chen, Jung-Hui
In this letter, we presented that the charge quantity is the critical factor for forming process. Forming is a pivotal process in resistance random access memory to activate the resistance switching behavior. However, overforming would lead to device damage. In general, the overshoot current has been considered as a degradation reason during the forming process. In this letter, the quantity of charge through the switching layer has been proven as the key element in the formation of the conduction path. Ultrafast pulse forming can form a discontinuous conduction path to reduce the operation power.
Conduction Mechanism and Improved Endurance in HfO2-Based RRAM with Nitridation Treatment
(2017-10-26)
Yuan, Fang-Yuan
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Deng, Ning
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Shih, Chih-Cheng
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Tseng, Yi-Ting
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Chang, Ting-Chang
A nitridation treatment technology with a urea/ammonia complex nitrogen source improved resistive switching property in HfO2-based resistive random access memory (RRAM). The nitridation treatment produced a high performance and reliable device which results in superior endurance (more than 10(9) cycles) and a self-compliance effect. Thus, the current conduction mechanism changed due to defect passivation by nitrogen atoms in the HfO2 thin film. At a high resistance state (HRS), it transferred to Schottky emission from Poole-Frenkel in HfO2-based RRAM. At low resistance state (LRS), the current conduction mechanism was space charge limited current (SCLC) after the nitridation treatment, which suggests that the nitrogen atoms form Hf-N-Ox vacancy clusters (V-o(+)) which limit electron movement through the switching layer.
Confirmation of filament dissolution behavior by analyzing electrical field effect during reset process in oxide-based RRAM
(2016-09-26)
Pan, Chih-Hung
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Chang, Kuan-Chang
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Chu, Tian-Jian
In this letter, we demonstrate completely different characteristics with different operating modes and analyze the electrical field effect to confirm the filament dissolution behavior. The device exhibited a larger memory window when using a single voltage sweep method during reset process rather than the traditional double sweep method. The phenomenon was verified by using fast I-V measurement to simulate the two operating methods. A better high resistance state (HRS) will be obtained with a very short rising time pulse, but quite notably, lower power consumption was needed. We proposed the electrical field effect to explain the phenomenon and demonstrate distribution by COMSOL simulation. Published by AIP Publishing.
Dehydroxyl effect of Sn-doped silicon oxide resistance random access memory with supercritical CO2 fluid treatment
(2012-09-10)
Tsai, Tsung-Ming
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Chang, Kuan-Chang
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Chang, Ting-Chang
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Syu, Yong-En
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Liao, Kuo-Hsiao
The tin-doped can supply conduction path to induce resistance switching behavior. However, the defect of tin-doped silicon oxide (Sn:SiOx) increased the extra leakage path lead to power consumption and joule heating degradation. In the study, supercritical CO2 fluids treatment was used to improve resistive switching property. The current conduction of high resistant state in post-treated Sn:SiOx film was transferred to Schottky emission from Frenkel-Poole due to the passivation effect. The molecular reaction model is proposed that the defect was passivated through dehydroxyl effect of supercritical fluid technology, verified by material analyses of x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4750235]
Effect of charge quantity on conduction mechanism of high-and low-resistance states during forming process in a one-transistor-one-resistor resistance random access memory
(2017-05-01)
Wu, Cheng-Hsien
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Chang, Kuan-Chang
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Chu, Tian-Jian
The forming process is a necessary and irreversible process to activate the resistance switching behavior in a resistance random access memory (RRAM) device. However, during the forming process, an overshoot current leads to device damage and causes inferior resistance switching characteristics; consequently, the process is considered to be a key factor in device degradation. In this paper, we find that a discontinuous conduction path can be formed by a pulse forming process such that the operation current can be reduced. We further investigate how the charge quantity during the forming process affects the carrier conduction mechanism of HRS, with all experiments and results demonstrated on onetransistor- one-resistor (1T1R) devices. (C) 2017 The Japan Society of Applied Physics
Effect of different constant compliance current for hopping conduction distance properties of the Sn:SiOx thin film RRAM devices
(2016-03)
Chen, Kai-Huang
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Chang, Kuan-Chang
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Liao, Kuo-Hsiao
To effectively lower the power consumption effect of Sn:SiO2 RRAM devices, the electrical hopping conduction mechanism for set/reset state was effectively used and achieved by different constant compliance current forming process. To assume and discuss the tin metal clustered reaction and electron transport behaviors in metallic filament path-forming model, the various electrical switching current and conduction mechanism model of the Sn:SiO2 RRAM devices for different constant compliance current were also investigated and described. Finally, the switching current relationship between hopping conduction energy and average inter-trap distance properties of the RRAM devices was also simulated and demonstrated in this study.
Effect of Electrode Material on Resistive Switching Characteristics in TaON Nonvolatile Memory Devices
(2013-01-01)
Chen, Min-Chen
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Chang, Ting-Chang
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Chiu, Yi-Chieh
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Chen, Shih-Cheng
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Huang, Sheng-Yao
The devices composed of Pt/TaON/TiN reveal bipolar switching behavior that shows excellent resistance ratio of 10(2) with operations over 100 DC cycles. The formation/disruption of conducting filaments by oxygen anions migration near/at the TiN electrode was applied to explain the switching behavior. In comparison with Pt/TaON/TiN device, the Cu/TaON/TiN device exhibits reversed bipolar resistive switching characteristic. The switching mechanism of Cu/TaON/TiN device is regarded as the Cu redox reaction and migration in the TaON film. Furthermore, the setting voltage of the Cu/TaON/TiN device is lower than that of the Pt/TaON/TiN device due to the confined conduction path by Cu filaments.