Browsing by Author "Wu, Pei-Yu"

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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.
Effect of Sputtered AlN Location on the Growth Mechanism of GaN
(2017-01-01)
Wu, Pei-Yu
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Li, Jhen-Hong
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Hsu, Lung-Hsing
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Huang, Chia-Yen
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Cheng, Yuh-Jen
Patterned sapphire substrates (PSSs) have been used to enhance the performance of GaN-based light-emitting diodes (LEDs). This performance can be further improved by using an ex situ sputtered AlN nucleation layer. This improvement has been attributed to the reduction of the GaN formation on the sidewall of the cone shape pattern. In this study, four kinds of PSS samples were fabricated to investigate the effect of sputtered AlN location on the growth mechanism of GaN in detail. (c) 2017 The Electrochemical Society. All rights reserved.
Growth of GaN on {12(3)over-bar5}-like Facets of Patterned Sapphire Substrate
(2017-01-01)
Wu, Pei-Yu
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Chen, Chien-Chih
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Huang, Chia-Yen
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Kuo, Hao-Chung
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Lin, Kun-Lin
GaN has been grown on wet-etched patterned sapphire substrate (PSS) by metal-organic chemical vapor deposition. It has been found that GaN was initiated not only from bottom c-facet but also from E {12 (3) over bar5} facets of hexagonal patterns/pyramids. In this study, a vacancy-PSS on c-plane sapphire was used to investigate the growth of GaN on the E-like facets (E1 and E2) of distorted pyramids. The results show that the orientation relationship between E1-GaN and sapphire is ((11) over bar2 (6) over bar) GaN // ((1) over bar 10 (2) over bar)(sapphire) and [11 (21) over bar] GaN // [11 (2) over bar0](sapphire). At the same time, that between E2-GaN and sapphire is (01 (14) over bar) GaN // (3 (3) over bar0 (6) over bar) sapphire and [02 (2) over bar1] GaN // [11 (2) over bar0] sapphire. (C) 2017 The Electrochemical Society. All rights reserved.
High-Performance Ultraviolet 385-nm GaN-Based LEDs With Embedded Nanoscale Air Voids Produced Through Atomic Layer Deposition and Al2O3 Passivation
(2016-04)
Liu, Che-Yu
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Huang, Chia-Yen
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Wu, Pei-Yu
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Huang, Jhih-Kai
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Kao, Tsung Sheng
This letter developed the high-performance GaN-based light-emitting diodes (LEDs) for ultraviolet (UV) light emission at 385 nm with the light output power enhanced by up to 52% compared with that of the conventional UV-LEDs. The high-power-efficiency UV-LEDs include sidewall-passivated Al2O3 dielectric nanoscale air voids, which were created using the atomic layer deposition method and act as intermediate media for improving the internal quantum efficiency, reducing threading dislocation, and relaxing strain. The fabricated air void nanostructure also enhanced the light extraction efficiency by similar to 32.7%, resulting in a high-power UV light-emitting device.
High-quality and highly-transparent AlN template on annealed sputter-deposited AlN buffer layer for deep ultra-violet light-emitting diodes
(2017-05-01)
Huang, Chia-Yen
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Wu, Pei-Yu
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Chang, Kai-Shiang
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Lin, Yun-Hsiang
;
Peng, Wei-Chih
A high-quality and highly-transparent AlN template was prepared by regrowth on a sputter-deposited AlN buffer layer. The buffer layer was thermally annealed and then underwent AlN regrowth in metalorganic chemical vapor deposition (MOCVD). The peakwidth of (002) and (102) plane x-ray rocking curve was 104 arcsec and 290 arcsec, respectively, indicating a threading dislocation density <5.0 x 10(8) cm(-2). Dislocations were reduced via grain growth and morphological evolution. The absence of carbon impurity source in sputter deposition also resulted in an improved transparency. According to transmission and reflection measurements, the absorption rate of lambda=280 nm emission propagating through the template was less than 6%. (C) 2017 Author(s).
Impact of electrode thermal conductivity on high resistance state level in HfO2-based RRAM
(2020-09-23)
Lin, Shih-Kai
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Wu, Cheng-Hsien
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Chen, Min-Chen
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Chang, Ting-Chang
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Lien, Chen-Hsin
This study examines the influence of different electrode thermal conductivity on switching behavior during the reset process. Electrical analysis methods and an analysis of current conduction mechanism indicate that better thermal conductivity in the electrode will require larger input power in order to induce more active oxygen ions to take part in the reset process. More active oxygen ions result in a more oxidized switching layer, and cause the effective switching gap (d(sw)) to become larger in the reset process. The effect of the electrode thermal conductivity and input power are explained by our model and clarified by electrical analysis methods.
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.
In vitro and in vivo imaging of peroxynitrite by a ratiometric boronatebased fluorescent probe
(2017-05-15)
Palanisamy, Sathyadevi
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Wu, Pei-Yu
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Wu, Shou-Cheng
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Chen, Yu-Jen
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Tzou, Shey-Cherng
Peroxynitrite (ONOO-) is an important species involved in many physiopathological processes. Progresses have been made in developing novel fluorescent probes to detect peroxynitrite with relatively high sensitivity and specificity. Herein, we report the synthesis, characterization and biological applications of a new boronate-based fluorescent probe, 4-MB. The studies showed that 4-MB exhibits a dual ratiometric and calorimetric response toward peroxynitrite due to ONOO--triggered oxidative reaction. A possible mechanism of the oxidation reaction was proposed and the reaction product was isolated and characterized using different spectroscopic methods. We have thoroughly demonstrated the utility of 4-MB for intracellular peroxynitrite imaging. Further, we showed that 4-MB can be potentially employed to visualize exogenous and endogenous peroxynitrite in RAW264.7 macrophages, EAhy926 cells, zebrafish and in live tissues from a high-fat diet-induced obese mouse model.
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.
Overcoming Limited Resistance in 1T1R RRAM Caused by Pinch-Off Voltage During Reset Process
(2019-11-01)
Zheng, Hao-Xuan
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Chen, Min-Chen
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Chang, Ting-Chang
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Su, Yu-Ting
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Chen, Wen-Chung
This article explains the difference in the reset processes between single RRAM and 1T1R RRAM structures. In the single RRAM, as the reset voltage increases, the off-state resistance increases. This is a normal RRAM operation. However, in the 1T1R structure, the reset voltage increases while the OFF-state resistance does not increase. This may be caused by either current or voltage being insufficient to switch the RRAM to its higher resistance state. The measurements of real voltage indicate that the insufficient voltage is in fact the main cause. For the 1T1R RRAM structure, if it is to be reset to a higher resistance state, it is best done by increasing the gate voltage to increase the OFF-state resistance. Therefore, we provide a method to reduce the misjudgment in the array, and it would be beneficial for the development of high-density memory.
Performance improvement after nitridation treatment in HfO2-based resistance random-access memory
(2018-08-01)
Wang, Ming-Hui
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Chang, Ting-Chang
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Shih, Chih-Cheng
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Tseng, Yi-Ting
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Tsai, Tsung-Ming
Nitrogen atoms were introduced into a Pt/HfO2/TiN resistance random-access memory (RRAM) device to improve the resistive switching characteristics induced by a high-pressure nitridation treatment. Compared with a similar untreated HfO2 device, it exhibited superior performance, including a lower forming voltage, a higher on/off ratio, and high-endurance cycle operations. Current-voltage curve-fitting results confirmed the difference of the carrier transport mechanisms after the nitridation treatment. Finally, a reaction model was proposed to explain the improvement of RRAM switching due to the introduction of nitrogen atoms. (C) 2018 The Japan Society of Applied Physics
Suppressing the Initial Growth of Sidewall GaN by Modifying AlN-Coated Patterned Sapphire with KOH-Based Etchant
(2019-10-29)
Hsu, Wen-Yang
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Lian, Yuan-Chi
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Wu, Pei-Yu
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Yong, Wei-Min
;
Sheu, Jinn-Kong
Micron-sized patterned sapphire substrates (PSSs) with an ex situ sputtered AlN nucleation layer (NL) have been used to improve the performance of GaN-based light-emitting diodes (LEDs). The growth of GaN was enhanced not only from bottom c-plane, but also from the sidewall of the micron-sized patterns. In this study, KOH solution was used to etch AlN (especially sidewall AlN) for the first time. The additional etching process is very simple. It was found that KOH etching 1 min did enhance the light output power (LOP) of LED. However, with the increase of etching time to 4 min, the LOP decreased. Besides, the effect of remained AlN on GaN growth mechanism was investigated in detail. (C) The Author(s) 2019. Published by ECS.
Suppressing the Initial Growth of Sidewall GaN by Modifying Micron-Sized Patterned Sapphire Substrate with H3PO4-Based Etchant
(2018-12-01)
Hsu, Wen-Yang
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Lian, Yuan-Chi
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Wu, Pei-Yu
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Yong, Wei-Min
;
Sheu, Jinn-Kong
Micron-sized patterned sapphire substrates (PSS) are used to improve the performance of GaN-based light-emitting diodes (LEDs). However, the growth of GaN is initiated not only from the bottom c-plane but also from the sidewall of the micron-sized patterns. Therefore, the coalescence of these GaN crystals creates irregular voids. In this study, two kinds of nucleation layers (NL)ex-situ AlN NL and in-situ GaN NLwere used, and the growth of sidewall GaN was successfully suppressed in both systems by modifying the micron-sized PSS surface.