Browsing by Author "Yang, Chih-Cheng"

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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
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Chen, Po-Hsun
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Shih, Chih-Cheng
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Wang, Ming-Hui
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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.
Improvement of Resistive Switching Characteristics in Zinc Oxide-Based Resistive Random Access Memory by Ammoniation Annealing
(2020-03-01)
Wu, Pei-Yu
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Zheng, Hao-Xuan
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Shih, Chih-Cheng
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Chang, Ting-Chang
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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.
Indium Diffusion Behavior and Application in HfO2-Based Conductive Bridge Random Access Memory
(1970-01-01)
Zheng, Hao-Xuan
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Shih, Chih-Cheng
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Chang, Ting-Chang
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Shih, Lin-Yi
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Shih, Yao-Kai
This study proposes the design of conductive bridge random access memory (CBRAM) using an indium electrode, which diffuses into hafnium oxide. The device is found to exhibit good operating characteristics, maintaining a large operation window, low set and reset voltages, and advantageous operation speed, thereby reducing operating power consumption. Electrical experiments, transmission electron microscopy, and energy-dispersive spectroscopy confirm that the device exhibits the characteristics of a CBRAM device. In addition, due to the large operation window of this In electrode device, a combination of two of these CBRAM can act as a complementary resistive switching (CRS) device with a large memory window.
Modifying Indium-Tin-Oxide by Gas Cosputtering for Use as an Insulator in Resistive Random Access Memory
(2016-11)
Chen, Po-Hsun
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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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Pan, Chih-Hung
In this paper, indium-tin-oxide (ITO) was used to act as both insulator and top electrode in resistive random access memory (RRAM) on identical bottom substrates. This is achieved by cosputtering an ITO target with nitride (N-2) or oxygen (O-2) gas as the insulator; then capping by an ITO electrode, such that both the rectifier and RRAM characteristics can be achieved before and after a forming process, respectively. In contrast, using pure ITO as an insulator does not exhibit RRAM behavior. To verify the rectifier and RRAM characteristics, material analyses and electrical measurements at various temperatures were conducted. Reliability tests including retention and endurance were also applied to verify the resistance switching stability. Finally, the rectifier and RRAM conduction models were proposed to examine the resistance switching behaviors. By applying the ITO material as both electrode and insulator, the resistance switching characteristic with high reliability is thus obtained.
Phase characterization and tunable photoluminescence of Eu-doped strontium-substituted nanohalophosphate
(2006-07-15)
Yang, Chih-Cheng
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Chen, San-Yuan
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Liu, Dean-Mo
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交大名義發表
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National Chiao Tung University
Nanocrystalline Eu-doped powders, Ca5-xSrx(PO4)(3)(OH):Eu3+, were prepared from chemical solutions at room temperature. The crystalline phase and photo luminescence (PL) properties of the halophosphate powders were studied in terms of solution pH value and annealing atmosphere. At pH = 2, both Ca8.3Sr1.7(PO4)(6)Cl-2 and Ca8.3Sr1.7(PO4)(6)(OH)(2) phases were detected, but an increase in solution pH value over 7 led to the formation of only Ca8.3Sr1.7(PO4)(6)(OH)(2) phase. After annealed at 850 degrees C, the sample prepared in pH = 2 solution shows stronger blue emission than that prepared in pH = 10 in the reducing atmosphere. However, for the samples annealed in air atmosphere, the blue emission still can be observed that can be attributed to the reduction of Eu3+ -> Eu2+. The relative intensity of blue to red emissions is dominated not only by annealing atmosphere but also by crystalline phase formed in the sample. These results indicate that the PL properties can be tunable by controlling the solution pH value (crystalline phase) and changing annealing atmosphere. (c) 2006 Elsevier B.V. All rights reserved.
Suppression of endurance degradation by applying constant voltage stress in one-transistor and one-resistor resistive random access memory
(2017-01-01)
Su, Yu-Ting
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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 an operation method that effectively suppresses endurance degradation. After many operations, the off-state of resistance random access memory (RRAM) degrades. This degradation is caused by reduction of active oxygen ions participating in the set process, as determined by current fitting of current-voltage (I-V) curves obtained from the endurance test between the interval of seventy to one hundred million operations. To address this problem, we propose the application of constant voltage stress after every five million operations during the endurance test. The experimental result shows that this method can maintain oxygen ions at the proper depth in the electrode and improve RRAM reliability. (c) 2017 The Japan Society of Applied Physics
The influence of temperature on set voltage for different high resistance state in 1T1R devices
(2019-02-01)
Tan, Yung-Fang
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Su, Yu-Ting
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Chen, Min-Chen
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Chang, Ting-Chang
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Tsai, Tsung-Ming
HfO2-based 1T1R is researched in this paper. The on-off ratio is an important electrical characteristic of RRAM, with a larger on-off ratio being preferable. However, temperature also affects the set process when operating RRAM. This study finds that the set process has different sensitivities to temperature at different high resistance states (HRSs). The set voltage of the higher HRS decreases with increasing temperature, while in the lower HRS, set voltage is independent of temperature. From the result, the lower HRS is better for RRAM because it is stable at different temperatures. (C) 2019 The Japan Society of Applied Physics