Browsing by Author "Sze, Simon M."

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A characteristic improved technique and analysis with plasma treatment to the electrode on oxide-based resistive random access memory
(2020-03-15)
Lin, Chih-Yang
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Chang, Ting-Chang
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Pan, Chih-Hung
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Chen, Min-Chen
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Xu, You-Lin
A technique was proposed to concentrate the distribution of set voltages. After a plasma treatment, the stability of the high-resistive state (HRS) increased, and the distribution of set voltages was more concentrated at 0.8 V, with a sufficient HRS/LRS resistive ratio (similar to 100x). In addition, the surface of the TiN electrode became rougher, causing oxygen to enter the TiN electrode and form a TiON layer, which acts as an oxygen reservoir. The reservoir is confirmed and the conduction model is supported by both electrical and material analyses. We propose that the observed improvement is due to the difference in the TiN electrode surface. (C) 2019 Published by Elsevier B.V.
A fabrication of germanium nanocrystal embedded in silicon-oxygen-nitride layer
(2006)
Tu, Chun-Hao
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Chang, Ting-Chang
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Liu, Po-Tsun
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Liu, Hsin-Chou
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Weng, Chi-Feng
The formation of germanium nanocrystals embedded in silicon-oxygen-nitride (SiON) layer acting as distributed charge storage elements is proposed in this work. A large memory window is observed due to the isolated Ge nanocrystals in the SiON gate stack layer. The Ge nanocrystals were nucleated after the high-temperature oxidation of SiGeN layer. The nonvolatile memory device with the Ge nanocrystals embedded in SiON stack layer exhibits 4 V threshold voltage shift under 7 V write operation. Also, the sequent high-temperature oxidation of the SiGeN layer acting as the blocking oxide is proposed to enhance the performance of nonvolatile memory devices. (c) 2006 The Electrochemical Society.
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 High Resistive State Current Mechanism Transformation in Ti/HfO2/TiN Resistive Random Access Memory
(2020-02-01)
Zhou, Kuan-Ju
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Chang, Ting-Chang
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Lin, Chih-Yang
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Chen, Chun-Kuei
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Tseng, Yi-Ting
In this letter, the electrical characteristics of Ti/HfO2/TiN resistive random access memory (RRAM) were thoroughly investigated. An abnormal current degradation was seen in the DC sweeping cycle. Both the on-state and off-state current clearly exhibited degradation with time. Next, current fitting analysis was used to investigate the carrier transport mechanisms. The results indicate that the on-state carrier transport mechanism changed from space-charge-limited current into hopping conduction after cycle sweeping. However, the off-state current changes from Schottky thermal emission to hopping conduction. Based on comparisons of different Schottky distances and Schottky barriers, physical models were proposed to explain the abnormal current degradation behavior. Finally, COMSOL electric field simulations were used to show the electric field distribution around the conducting filament (CF), and the conducting model was subsequently verified.
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 Au-free GaN High Electron Mobility Transistor with Ti/Al/W Ohmic Metal Structure
(2015)
Yao, Jing-Neng
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Lin, Yueh-Chin
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Chuang, Yu-Lin
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Huang, Yu-Xiang
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Shih, Wang-Cheng
We demonstrate the Au-free GaN HEMT device with the Ti/Al/W Ohmic metal structure. Excellent surface roughness 4.88nm for Ti/Al/W Ohmic stucture was achieved after metallization. The DC characteristics is comparable with conventional HEMTs and the stress performance with high voltage is better than conventional HEMTs.
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 an anomalous hump in gate current after dynamic negative bias stress in HfxZr1-xO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors
(1970-01-01)
Ho, Szu-Han
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Chang, Ting-Chang
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Wu, Chi-Wei
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Lo, Wen-Hung
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Chen, Ching-En
"This letter investigates a hump in gate current after dynamic negative bias stress (NBS) in HfxZr1-xO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. By measuring gate current under initial through body floating and source/drain floating, it shows that hole current flows from source/drain. The fitting of gate current-gate voltage characteristic curve demonstrates that Frenkel-Poole mechanism dominates the conduction. Next, by fitting the gate current after dynamic NBS, in the order of Frenkel-Poole then tunneling, the Frenkel-Poole mechanism can be confirmed. These phenomena can be attributed to hole trapping in high-k bulk and the electric field formula Ehigh-k epsilon(high-k) = Q + E-sio2 epsilon(sio2). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4739525]"
Analysis of anomalous traps measured by charge pumping technique in HfO2/metal gate n-channel metal-oxide-semiconductor field-effect transistors
(2012-12-03)
Ho, Szu-Han
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Chang, Ting-Chang
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Lu, Ying-shin
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Lo, Wen-Hung
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Chen, Ching-En
This letter investigates anomalous traps measured by charge pumping technique in high voltage in HfO2/metal gate n-channel metal-oxide-semiconductor field-effect transistors. N-V-high level characteristic curves with different duty ratios indicate that the electron discharge time dominates the value of N for extra traps. By fitting ln (N (t(base level) = 2.5 mu s)-N (t(base level)))-Delta t(base level) at different temperatures and computing the equation t = tau(0) exp (alpha(e,SiO2)d(SiO2) + alpha(e,HfO2)d(HfO2,trap)), results show that these extra traps measured by the charge pumping technique at high voltage can be attributed to high-k bulk shallow traps. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4769444]
Analyzing Electric Field Effect by Applying an Ultra-Short Time Pulse Condition in Hafnium Oxide-Based RRAM
(2018-08-01)
Wu, Cheng-Hsien
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Lin, Shih-Kai
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Pan, Chih-Hung
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Chen, Po-Hsun
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Lin, Wen-Yan
In this letter, we determine the importance of the electrical field distribution and strength during the switching process by demonstrating different trends in the degree of reset and the reset pulse time. In general, a longer reset pulse time results in a higher reset energy; a higher reset energy leads to a higher degree of reset, which we obtainedby applying different width square waves. But quite notably, the opposite result was obtained using triangle waves, where a higher degree of reset occurred with a shorter rising time and lower reset energy. We believe that this is due to the electric field effect: if the voltage rises faster than the filament oxidation, the device can produce a larger effective electric field and a higher resistance in the reset process. To further investigate the mechanism, the procedure of the reset process was analyzed in detail, and COMSOL simulation is also carried out for confirmation.
Annealing effects on resistive switching of IGZO-based CBRAM devices
(2020-10-01)
Gan, Kai-Jhih
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Liu, Po-Tsun
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Ruan, Dun-Bao
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Chiu, Yu-Chuan
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Sze, Simon M.
In this study, the impact of post-oxide deposition annealing on performance of IGZO-based conductive-bridging random access memory (CBRAM) is reported. It is found that besides the distinct reduction in resistive switching parameters of SET/RESET voltages, their dispersions, and the resistance ratio of high-resistance state to low-resistance state can be improved after N-2 annealing. The annealing effects on enhancing of the resistive switching properties are investigated by x-ray photoelectron spectra. It can be considered that the formation of the filament is better controlled by the increase of oxygen vacancies in the switching layer, which is the main reason for the improvement of resistive switching characteristics.
Anomalous Gate Current Hump after Dynamic Negative Bias Stress and Negative-Bias Temperature-Instability in p-MOSFETs with HfxZr1-xO2 and HfO2/Metal Gate Stacks
(2013)
Ho, Szu-Han
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Chang, Ting-Chang
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Wu, Chi-Wei
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Lo, Wen-Hung
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Chen, Ching-En
In this study, the authors investigated an anomalous gate current hump after dynamic negative bias stress (NBS) and negative-bias temperature-instability (NBTI) in HfxZr1-xO2 and HfO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. This result is attributed to hole trapping in high-k bulk. Measuring gate current under initial through body floating and source/drain floating conditions indicates that holes flow from source/drain to gate. The fitting of the gate current-gate voltage characteristic curve demonstrates that Frenkel-Poole mechanism dominates the conduction under initial. Next, fitting the gate current after dynamic NBS and NBTI indicates Frenkel-Poole then tunneling mechanisms, finally returning to the Frenkel-Poole mechanism. These phenomena can be attributed to hole trapping in high-k bulk and the formula Ehigh-k epsilon(high-k) = Q + E-sio2 epsilon(sio2). To further understand the gate current hump, both Zr-undoped and 8 similar to 10% Zr-doped in high-k bulk devices were used for comparisons. These results indicate that initial gate current is also a significant factor in generating the anomalous gate current hump, and all results obey the hump generation condition of J(Tunneling) << J(Frenkel-Poole). (C) 2013 The Electrochemical Society. All rights reserved.
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.
Bipolar Resistive Switching Characteristics of Transparent Indium Gallium Zinc Oxide Resistive Random Access Memory
(2010)
Chen, Min-Chen
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Chang, Ting-Chang
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Huang, Sheng-Yao
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Chen, Shih-Ching
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Hu, Chih-Wei
This study investigates a sputtered InGaZnO (IGZO) thin film to apply into a resistive random access memory device. After the formation of an indium tin oxide (ITO)/IGZO/ITO structure at room temperature, the device exhibits a repeatable bipolar resistance switching behavior without an electroforming process and an excellent transmittance in the visible region. The conduction mechanisms for low and high resistance states are dominated by Ohm's law and space-charge-limited current behavior, respectively. In retention and endurance tests, a resistance ratio of more than 1 order remains after 10(4) s at 90 degrees C and after 100 dc voltage sweeping cycles. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3360181] All rights reserved.
Bipolar resistive switching characteristics of tungsten-doped indium-zinc oxide conductive-bridging random access memory
(2019-08-01)
Gan, Kai-Jhih
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Liu, Po-Tsun
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Lin, Sheng-Jie
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Ruan, Dun-Bao
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Chien, Ta-Chun
The purpose of this work is to develop a reliable amorphous tungsten-doped indium-zinc oxide based conductive-bridging random access memory (CBRAM). The device with Cu/TiW/InWZnO/Pt structure exhibits stable bipolar resistive switching behavior. The device also shows good non-volatile memory characteristics, such as low operation voltage, on/off resistance ratio (similar to 10(2)), high switching endurance (more than 5 x 10(2) cycles). The temperature coefficient of resistance in the conductive filament confirms that an electro-chemical metallization (ECM) based conduction is observed in the InWZnO device. Furthermore, the temperature retention characteristics and the current transport mechanisms are also investigated. According to our experiments, we propose a model to explain the resistive switching phenomenon observed in our devices. These results have given a great potential for the transparent amorphous oxide semiconductor (TAOS)-based material utilizing in CBRAM stacks and integrating into the display circuits for future memory-in-pixel applications.
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.