Browsing by Author "Huang, Hui-Chun"

Now showing 1 - 20 of 44

A Dual-Gate InGaZnO4-Based Thin-Film Transistor for High-Sensitivity UV Detection
(2019-08-01)
Chen, Po-Hsun
;
Tsao, Yu-Ching
;
Chien, Yu-Chieh
;
Chiang, Hsiao-Cheng
;
Chen, Hua-Mao
UV-sensing devices have received significant recent attention for applications in areas such as human health, fire detection, and optical communication. One key factor for product commercialization is determining the optimal materials that allow for integration of excellent UV-sensing properties with compatibility with industrial fabrication processes. However, current UV sensors often fail to achieve this due to either mismatched materials or a device that must be excessively large in order to produce enough photocurrent for UV detection. The UV-light-sensing properties of an amorphous InGaZnO4 (IGZO) thin-film transistor with a dual-gate structure and relatively small device size (width/length = 50 mu m/10 mu m) that achieves high sensitivity through a threshold-voltage-(V-th)-adjustment method is proposed. Comparing the drain currents under UV exposure to those under darkened conditions indicates that the ratio between the photoinduced and dark current reaches 10(6). Furthermore, the UV sensitivity of the dual-gate transistors can be adjusted by varying the bottom gate voltage, with each pixel of the sensor then being read out separately via scan line pulses. This allows the dual-gate a-IGZO transistor to be used for high-performance UV sensing while being effectively integrated in display applications.
Abnormal hysteresis formation in hump region after positive gate bias stress in low-temperature poly-silicon thin film transistors
(2020-09-30)
Tu, Hong-Yi
;
Chang, Ting-Chang
;
Tsao, Yu-Ching
;
Tai, Mao-Chou
;
Tsai, Yu-Lin
Degradation in low-temperature polycrystalline-silicon thin-film transistors after electrical stress was thoroughly investigated in this work. Main channel degradation, abnormal hump generation and hysteresis appearing in the hump region can be observed after positive bias stress. Furthermore, the difference in subthreshold swing (SS) values between forward/reverse sweep is observed. The electron trapping into the gate insulator (GI) dominates the main degradation and the hump generation. Additionally, the difference in SS values which appears in the hump region is attributed to the interface traps and the hysteresis is caused by electron trapping/detrapping into GI.
An Electronic Synapse Device Based on Solid Electrolyte Resistive Random Access Memory
(2015-08-01)
Zhang, Wei
;
Hu, Ying
;
Chang, Ting-Chang
;
Chang, Kuan-Chang
;
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.
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
;
Chen, Po-Hsun
;
Chang, Ting-Chang
;
Chang, Kuan-Chang
;
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
;
Chang, Kuan-Chang
;
Chang, Ting-Chang
;
Syu, Yong-En
;
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
;
Tsai, Tsung-Ming
;
Chang, Ting-Chang
;
Wu, Hsing-Hua
;
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.
Effect of ELA Energy Density on Self-Heating Stress in Low-Temperature Polycrystalline Silicon Thin-Film Transistors
(2020-08-01)
Huang, Shin-Ping
;
Chen, Hong-Chih
;
Chen, Po-Hsun
;
Zheng, Yu-Zhe
;
Chu, Ann-Kuo
The extent of the poly-silicon crystalline protrusion, a result of differences in excimer laser annealing (ELA), affects the performance and reliability of thin-film transistors (TFTs). This study investigates the degradation mechanism of the low-temperature polycrystalline silicon (LTPS) TFT devices with differences in crystalline protrusion under self-heating stress (SHS). Higher ELA energy will induce higher protrusion height in the interface between the poly-silicon and gate insulator (GI). This surface morphology leads to serious charge trapping into the GI layers; in contrast, the smallest degradation after SHS can be seen in the devices with the lowest protrusion height. This indicates that the degradation is caused by the surface morphology between the poly-Si and GI interface. In addition, the COMSOL simulation results confirm that the large electric field in the GI layer appears in the rough surface morphology devices; therefore, choosing the appropriate ELA energy of the poly-Si is beneficial for the applications of the driving TFT in organic light-emitting diode (OLED) display in the manufacturing industry.
Effect of Electrode Material on Resistive Switching Characteristics in TaON Nonvolatile Memory Devices
(2013-01-01)
Chen, Min-Chen
;
Chang, Ting-Chang
;
Chiu, Yi-Chieh
;
Chen, Shih-Cheng
;
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.
Effect of SiO2 Buffer Layer Thickness on Performance and Reliability of Flexible Polycrystalline Silicon TFTs Fabricated on Polyimide
(2016-12-01)
Chen, Bo-Wei
;
Chang, Ting-Chang
;
Hung, Yu-Ju
;
Huang, Shin-Ping
;
Chen, Hua-Mao
This letter investigates flexible polycrystalline silicon thin film transistor performance variation due to different buffer layer thicknesses. In flexible electronics, thermal expansion stress during device fabrication is inevitable. A thicker SiO2 buffer demonstrates better endurance to thermal expansion stress from the polyimide substrate during device annealing. However, if the SiO2 buffer thickness is above a critical point, its weak heat dissipation capability causes the optimal ELA crystallization condition to shift. A thermal expansion stress simulation and TEM photos were utilized to verify performance variation. Furthermore, a similar trend was observed in electrical characteristics after negative bias temperature instability.
Effects of erbium doping of indium tin oxide electrode in resistive random access memory
(2016-03)
Chen, Po-Hsun
;
Chang, Kuan-Chang
;
Chang, Ting-Chang
;
Tsai, Tsung-Ming
;
Pan, Chih-Hung
Identical insulators and bottom electrodes were fabricated and capped by an indium tin oxide (ITO) film, either undoped or doped with erbium (Er), as a top electrode. This distinctive top electrode dramatically altered the resistive random access memory (RRAM) characteristics, for example, lowering the operation current and enlarging the memory window. In addition, the RESET voltage increased, whereas the SET voltage remained almost the same. A conduction model of Er-doped ITO is proposed through current-voltage (I-V) measurement and current fitting to explain the resistance switching mechanism of Er-doped ITO RRAM and is confirmed by material analysis and reliability tests. (C) 2016 The Japan Society of Applied Physics
Endurance Improvement Technology With Nitrogen Implanted in the Interface of WSiOx Resistance Switching Device
(2013-07-01)
Syu, Yong-En
;
Zhang, Rui
;
Chang, Ting-Chang
;
Tsai, Tsung-Ming
;
Chang, Kuan-Chang
Incorporation of nitrogen as an oxygen-confining layer in the resistance switching reaction region is investigated to improve the reliability of resistance random access memory (RRAM). The switching mechanism can be attributed to the formation and rupture of conduction filaments. A compatible WSiON (around 5 nm) layer is introduced at the interface of tungsten silicon oxide (WSiOx) and TiN electrode to prevent the randomly diffusing oxygen ions surpassing the storage region of the WSiON layer. The double-layer WSiOx/WSiON memory structure would enhance the endurance over 100 times so as to better confirm the WSiOx RRAM application of nonvolatile memory.
Engineering interface-type resistance switching based on forming current compliance in ITO/Ga2O3: ITO/TiN resistance random access memory: Conduction mechanisms, temperature effects, and electrode influence
(2016-10-31)
Pan, Chih-Hung
;
Chang, Ting-Chang
;
Tsai, Tsung-Ming
;
Chang, Kuan-Chang
;
Chen, Po-Hsun
In this paper, an ITO/Ga2O3: ITO/TiN structured resistance random access memory is introduced. Either interface or filament conduction mechanism can be induced depending on the forming compliance current, which has not been investigated before. Material analyses and electrical I-V measurements on this ITO/Ga2O3: ITO/TiN have also been carried out. The interface conduction mechanism was confirmed by a size-effect experiment, where resistance varied inversely to via size. In addition, the current fitting results show that Schottky emission dominates the on-and off-state currents. All physical mechanisms of device resistive switching behaviors are explained by our models and also confirmed by I-V characteristics. Published by AIP Publishing.
Enhancement of Surface Chemical and Physical Properties of Germanium-Sulfur Thin Film Using a Water-Supplemented Carbon Dioxide Supercritical Fluid Treatment Technique
(2018-11-09)
Yang, Chih-Cheng
;
Chen, Po-Hsun
;
Shih, Chih-Cheng
;
Wang, Ming-Hui
;
Tsai, Tsung-Ming
In this study, an oxidation treatment technique suitable for the material and electronic device applications proceeding at low temperature (only 80 degrees C) and high pressure (3000 psi) utilizing a carbon dioxide (CO2) supercritical fluid (SCF), also known as scCO(2), which is supplemented with water molecules, is reported. To demonstrate the possible effects on material and devices for the proposed SCF treatment, an amorphous germanium-sulfur (GeS) thin film and a GeS-based resistance random access memory (RRAM) device are prepared. After the SCF treatment, electrical measurements confirm that the GeS-based RRAM device exhibits a lower forming voltage, more stable resistance switching characteristics, and higher concentration distributions of high and low resistance states when compared to the device without SCF treatment. As for the material effects, both chemical and physical properties are examined based on material analyses results. It is concluded that the original amorphous GeS thin film transforms to a polycrystallized GeO film, confirmed by a reaction model for the SCF treatment illustrating possible oxidation and crystallization effects induced by this SCF treatment. This water-enhanced scCO(2) SCF treatment technique, thus, shows its capability as a feasible synthetic method for material modification as well as suitability for device level applications.
Enhancement of the stability of resistive switching characteristics by conduction path reconstruction
(2013-07-22)
Huang, Jheng-Jie
;
Chang, Ting-Chang
;
Yu, Chih-Cheng
;
Huang, Hui-Chun
;
Chen, Yu-Ting
In this study, a Pt/BiFeO3/TiN device was fabricated and the resistance switching characteristics were investigated. After the first forming process, the conduction path was formed and exhibited unstable bipolar switching characteristics. Subsequently, the original conduction path was destroyed thoroughly by high negative bias. By reconstructing the conduction path after a second forming process (re-forming process), the device exhibits stable bipolar switching characteristics. Transmission electron microscopy analysis indicates that the stability of switching behavior was enhanced because of the joule heating effect, and is an easy way to improve the resistance switching characteristics. (C) 2013 AIP Publishing LLC.
Formation and composition of titanium oxinitride nanocrystals synthesized via nitridizing titanium oxide for nonvolatile memory applications
(2011-09-01)
Feng, Li-Wei
;
Chang, Chun-Yen
;
Chang, Ting-Chang
;
Tu, Chun-Hao
;
Wang, Pai-Syuan
Formation and composition analyses of titanium oxinitride nanocrystals (NCs) fabricated via treating a magnetron co-sputtered thin film of titanium and silicon dioxide with a rapid thermal annealing in nitrogen ambient were demonstrated for nonvolatile memory applications. Phase separation characteristics with different annealing conditions were examined by transmission electron microscopy and chemical bonding characteristics were confirmed by X-ray photon emission spectra. It was observed that a blanket layer composed mainly of titanium oxide was still present as annealing temperature was increased to 700 degrees C, associated with the thermodynamically stable phase of titanium oxide. Furthermore, a higher thermal treatment of 900 degrees C induced formation of a well-separated NC structure and caused simultaneously partial nitridation of the titanium oxide, thereby forming titanium oxinitride NCs. A significant capacitance-voltage hysteresis in threshold voltage shift at 1 V was easily achieved under a small sweeping voltage range of + 2 V/-2 V, and a memory window retention of 2.2 V was obtained after 10(7) s by extrapolation under a 1 s initial-program/erase condition of +5 V/-5 V, respectively. (C) 2011 Elsevier B.V. All rights reserved.
Hopping Effect of Hydrogen-Doped Silicon Oxide Insert RRAM by Supercritical CO2 Fluid Treatment
(2013-05-01)
Chang, Kuan-Chang
;
Pan, Chih-Hung
;
Chang, Ting-Chang
;
Tsai, Tsung-Ming
;
Zhang, Rui
In this letter, we introduced hydrogen ions into titanium metal doped into SiO2 thin film as the insulator of resistive random access memory (RRAM) by supercritical carbon dioxide (SCCO)(2) fluid treatment. After treatment, low resistance state split in to two states, we find the insert RRAM, which means it has an operating polarity opposite from normal RRAM. The difference of the insert RRAM is owing to the resistive switching dominated by hydrogen ions, dissociated from OH bond, which was not by oxygen ions as usual. The current conduction mechanism of insert RRAM was hopping conduction due to the metal titanium reduction reaction through SCCO2.
Improvement in the bias stability of amorphous InGaZnO TFTs using an Al2O3 passivation layer
(2013-09-01)
Huang, Sheng-Yao
;
Chang, Ting-Chang
;
Chen, Min-Chen
;
Chen, Te-Chih
;
Jian, Fu-Yen
This work presents the light-color-dependent negative bias stress (NBIS) effect on amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) with Al2O3 passivation layer. The colors of incident photon are varied from red to blue, that incident photon energies are all lower than the optical band gap of IGZO (3.2 eV). The experimental results show that the Al2O3 passivated devices present stable electrical behaviors under different incident lights (Delta V-T<0.1 V of dark and red, Delta V-T<1 V of green, and Delta V-T<4 V of blue), whereas the unpassivation devices exhibit observable negative shifts during NBIS (Delta V-T<1 V of dark and red, Delta V-T>8 V of green, and Delta V-T>15 V of blue). The degradation mechanism of the negative bias stress under illumination of a-IGZO TFTs is dominated by the photo-generated hole trapping at the gate insulator and/or interface between insulator and channel. In this result, the Al2O3 passivation layer can effectively passivate the defect in the a-IGZO film, reducing electron hole pair generated during the illumination processed. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.
Improvement of Resistive Switching Characteristic in Silicon Oxide-Based RRAM Through Hydride-Oxidation on Indium Tin Oxide Electrode by Supercritical CO2 Fluid
(2015-06-01)
Chang, Kuan-Chang
;
Tsai, Tsung-Ming
;
Chang, Ting-Chang
;
Zhang, Rui
;
Chen, Kai-Huang
Supercritical carbon dioxide (SCCO2) fluid technology was applied to indium-tin-oxide (ITO) electrode to improve the resistive switching characteristic of silicon oxide RRAM through hydride oxidation for the first time. We found device power consumption can be effectively reduced so that side effects can be also restricted under device operation. By applying SCCO2 fluid, more oxygen ions will be introduced into the ITO electrode and thus the participation of net oxygen ions in the RRAM redox reaction will increase. Fourier transform spectroscopy and X-ray photoelectron spectroscopy were used to confirm hydride oxidation on ITO electrode. Combined with the current fitting results, we proposed a reaction model to explain the improvement of resistive switching in RRAM by SCCO2 fluids.
Improvement of Resistive Switching Characteristics in Zinc Oxide-Based Resistive Random Access Memory by Ammoniation Annealing
(2020-03-01)
Wu, Pei-Yu
;
Zheng, Hao-Xuan
;
Shih, Chih-Cheng
;
Chang, Ting-Chang
;
Chen, Wei-Jang
In this experiment, the electrical performance of zinc oxide based-resistive random access memory (RRAM) is successfully improved by using annealing in ammonia hydroxide solution at low-temperature and high pressure to complete ammonium-doped ZnO based-RRAM. The results of material analysis indicate that using CO2 as ammonia hydroxide carrier during the annealing process leads to the reduction in dangling bond density. This can be clearly observed in the decrease in breakdown voltage during the forming process and a lower operating current during operation. Furthermore, in this ammonium-doped ZnO based-RRAM, we study the molecular doping of NH3 in ZnO, where the endurance and retention properties are improved as well. These improvements can be attributed to the higher concentration of nitrogen in the switching layer, which can effectively control the active oxygen ions during the operation process.
Improvement of the performance of ZnO TFTs by low-temperature supercritical fluid technology treatment
(2009-12-25)
Chen, Min-Chen
;
Chang, Ting-Chang
;
Huang, Sheng-Yao
;
Chang, Kuan-Chang
;
Huang, Hui-Chun
in this paper, the supercritical CO(2) (SCCO(2)) fluid technology is successfully applied to improve the electrical characteristics of sputtered ZnO TFTs at low temperature (150 degrees C). After the treatment of SCCO(2) fluids mixed with water, the ZnO TFT exhibited superior transfer characteristics and lower threshold voltage. According to X-ray photoelectron spectroscopy (XPS) analyses, the improvements were attributed to the increase of binding energies of Zn-O bonds, hydrogen-related donors and the reduction of traps at the grain boundaries in ZnO thin films. In addition, the crystalline quality and microstructure of ZnO thin films were also investigated by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The transmittance of the ZnO film was measured by an N&K analyzer 1280 (N&K Technology, Inc.), which is a new type of thin-film measurement system. (C) 2009 Elsevier B.V. All rights reserved.