Browsing by Author "Zheng, Zhi-Wei"

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Amorphous bilayer TiO2-InGaZnO thin film transistors with low drive voltage
(2014-09-01)
Hsu, Hsiao-Hsuan
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Cheng, Chun-Hu
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Chiou, Ping
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Chiu, Yu-Chien
;
Chang, Chun-Yen
This paper describes a high-performance thin-film transistor (TFT) fabricated using TiO2 and InGaZnO semiconducting layers. Favorable transistor characteristics, including a low threshold voltage of 0.45 V, a small subthreshold swing of 174 mV/decade, and a high field effect mobility of 19 cm(2)/V s at a low drive voltage of <2 V, were achieved. This favorable performance mainly resulted from the combined effect of the high-dielectric-constant gate dielectric and the TiO2-InGaZnO active semiconductor bilayer, which reduced the operating voltage, enhanced the device mobility, and improved the transistor gate swing. This TiO2-InGaZnO TFT exhibits great potential for future high-speed and high-resolution display applications. (C) 2014 Elsevier Ltd. All rights reserved.
Bipolar Conduction in Tin-Oxide Semiconductor Channel Treated by Oxygen Plasma for Low-Power Thin-Film Transistor Application
(2016-03)
Chen, Po-Chun
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Wu, Yung-Hsien
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Zheng, Zhi-Wei
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Chiu, Yu-Chien
;
Cheng, Chun-Hu
In this paper, we investigated the bipolar conduction mechanism in thin-film transistors (TFTs) with oxygen plasma treatment on tin-oxide channel. The optimized p-type thin-oxide TFTs showed an on/off ratio of >10(4), a threshold voltage of -1.05 V, and a field-effect mobility of 2.14 cm(2).V-1.s(-1). By increasing the exposure time of oxygen plasma, excess oxygen was incorporated to thin-oxide channel and converted thin monoxide to oxygen-rich n-type thin dioxide, which in turn led to n-type operation. It indicated that oxygen plasma was the critical factor to determine oxygen concentration, oxygen vacancies, metal ions and channel polarity. This proposed oxygen-content tuning through plasma treatment approach shows great promise in simplification of TFT process that can achieve n-type and p-type TFTs under the same device process.
Characteristic Simulation of Hybrid Multilayer Junctionless Field Effect Transistors with Negative Capacitance Effect
(2020-01-01)
Ma, Jun
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Liu, Chien
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Liu, Wei-Dong
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Hung, Yu-Wen
;
Fan, Yu-Chi
In this study, we reported a hybrid multi-PNPN channel junctionless field effect transistor (JLFET) with negative capacitance (NC) effect by simulation. By incorporating a ferroelectric HfAlO capacitor with NC effect, an extremely low subthreshold swing of 34 mVdecade, a very high onoff current ratio and a very low driven voltage were achieved in the NC-enhanced hybrid multi-PNPN channel JLFET. This novel device not only improves the on-state current reduction while channel scaling down, but also shows great potential for the next-generation low-power three-dimensional stacked integrated circuit applications.
Current Uniformity Improvement in Flexible Resistive Memory
(2013)
Zheng, Zhi-Wei
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Cheng, Chun-Hu
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Chou, Kun-I
;
Liu, Ming
;
Chin, Albert
High uniform current distribution, good endurance, and low 28 mu W switching power are successfully achieved in Ni/GeOx/TiOy/TaN resistive random access memory devices on flexible polyimide substrate. The good performances are attributed to the nitrogen-rich TaN to increase the oxidation resistance and decrease the TaON and oxygen vacancies formation from x-ray photoelectron spectroscopy measurements, where such oxygen vacancies are related to current conduction at high resistance state. The present results demonstrate that the device with nitrogen-rich TaN electrode has a strong potential for future low-cost high-performance flexible memory application.
Emission dynamics of GaN-based blue resonant-cavity light-emitting diodes
(2019-12-01)
Xu, Rong-Bin
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Xu, Huan
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Mei, Yang
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Shi, Xiao-Ling
;
Ying, Lei-Ying
We fabricated GaN-based blue resonant-cavity light-emitting diodes (RCLEDs) by inserting InGaN quantum well (QW) active region between two dielectric distributed Bragg reflectors (DBRs). Due to the different gain enhancement factors in a single device, multi-longitudinal modes were observed and tuned with changing the injection current density: pure-blue (PB) at low current density, violet-blue (VB) at intermediate current density, and PB again at high current density. The variation of emission spectra is explained by the competition between band-filling effect and self-heating effect.
Fast Low-Temperature Plasma Process for the Application of Flexible Tin-Oxide-Channel Thin Film Transistors
(2017-09-01)
Chen, Po-Chun
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Chiu, Yu-Chien
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Zheng, Zhi-Wei
;
Lin, Ming-Huei
;
Cheng, Chun-Hu
In this study, we demonstrated a p-type and n-type SnO TFTs on flexible polyimide substrate. The fabricated p-type SnO TFT showed a high I-on/I-off of 5.7 x 10(5) and a high mu(FE) of 10.7 cm(2) V-1 s(-1). Through optimizing the oxygen plasma condition, the n-type channel TFT transfered from prime p-type channel exhibits excellent characteristics, including a high on/off current ratio of 6.6 x 10(3), a low threshold voltage of -0.13 V, and a very high field-effect mobility of 28 cm(2) V-1 s(-1). This proposed low-temperature oxygen plasma treatment shows the potential in simplification of TFT process that can achieve n-type and p-type TFTs under the same device process.
Gamma-Ray Irradiation Effect on Ferroelectric Devices with Hafnium Aluminum Oxides
(2019-12-01)
Liu, Chien
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Tung, Yi-Chun
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Wu, Tian-Li
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Cheng, Chun-Hu
;
Tseng, Chih-Yang
Herein, the gamma-ray irradiation effect on ferroelectric HfAlO(x)capacitors for biomedical and space applications is investigated. The experimental results focus on the observation of ferroelectric polarization characteristics in support of different defect mechanisms induced by annealing, endurance cycling, and gamma-ray irradiation. It is found that the HfAlO(x)with low Al doping of 6.5% become more vulnerable to radiation exposure, but a remarkable improvement in 9%-Al-doped HfAlO(x)due to less oxygen vacancies is demonstrated. In addition, the results also confirm that the fatigue property of ferroelectric HfAlO(x)capacitor is determined by the electric-stress-induced defect during endurance cycling, not mainly contributed by irradiation damage, which shows the potential for memory applications in rigorous irradiation environment.
Improved current distribution in resistive memory on flexible substrate using nitrogen-rich TaN electrode
(2012-12-10)
Zheng, Zhi-Wei
;
Cheng, Chun-Hu
;
Chou, Kun-I
;
Liu, Ming
;
Chin, Albert
Narrow current distribution, good endurance, and low 28 mu W switching power are successfully achieved in Ni/GeOx/TiOy/TaN resistive random access memory devices. The good distribution and endurance are attributed to the nitrogen-rich TaN to increase the oxidation resistance and decrease the TaON and oxygen vacancies formation from x-ray photoelectron spectroscopy measurements, where such oxygen vacancies are related to current conduction at high resistance state. In addition, the devices on the flexible polyimide substrate exhibit excellent mechanical endurance upon repeated bending tests, showing their high potential for low-cost flexible memory application. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4772003]
Improved high-temperature switching characteristics of Y2O3/TiOx resistive memory through carrier depletion effect
(2014-05-01)
Zheng, Zhi-Wei
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Hsu, Hsiao-Hsuan
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Cheng, Chun-Hu
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Chen, Po-Chun
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電子工程學系及電子研究所
We report a stacked Y2O3/TiOx resistive random access memory (RRAM) device, showing good high-temperature switching characteristics of extremely low reset current of 1 A at 150 degrees C, large off/on resistance window (>200) at 150 degrees C, large rectification ratio of approximate to 300 at 150 degrees C and good current distribution at 85 degrees C. The good rectifying property, lower high-temperature sneak current and tighter high-temperature current distribution can be attributed to the combined results of the oxygen vacancies in TiOx and the related carrier depletion effect. ((c) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of plasma fluorination on p-type channel tin-oxide thin film transistors
(2017-06-15)
Chen, Po-Chun
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Chiu, Yu-Chien
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Zheng, Zhi-Wei
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Cheng, Chun-Hu
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Wu, Yung-Hsien
This paper describes a high-performance p-type tin-oxide (SnO) thin film transistor (TFT) using fluorine plasma treatment on the SnO active channel layer. The influence of fluorine plasma treatment for this p-type SnO TFT device was also investigated. Through tuning the fluorine plasma power treated on the SnO active channel layer at low temperature, the optimal p-type SnO TFT device exhibits a very high on/off current ratio of 9.6 x 10(6), a field-effect mobility of 2.13 cm(2) V-1 s(-1), a very low subthreshold swing of 106 mV/dec and an extremely low off-state current of 1 pA at a low driven voltage of <3 V. These good characteristics can be attributed to fluorine plasma treatment on p-type SnO channel that reduced crystallized channel roughness and passivated oxygen vacancies and interface traps. This high-performance p-type SnO TFT device using fluorine plasma treatment on the active channel shows great promise for future high-resolution and high-speed display applications. (C) 2016 Elsevier B.V. All rights reserved.
Investigation on polarization characteristics of ferroelectric memories with thermally stable hafnium aluminum oxides
(2019-08-01)
Chang, Tun-Jen
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Liu, Chien
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Fan, Chia-Chi
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Hsu, Hsiao-Hsuan
;
Chen, Hsuan-Han
In this work, we successfully demonstrated the 9.6-nm-thick HfAlOx ferroelectric memory using light aluminium doping of 6.5% to form ferroelectric orthorhombic phase. Compared to ferroelectric HfZrOx film with zirconium diffusion issue, the HfAlOx film showed excellent thermal stability under high temperature annealing. Besides, the ferroelectric HfAlOx also exhibited robust polarization characteristics under endurance cycling test. A > 10(6) stressed cycles with 4 MV/cm can be measured and a long endurance was sustained over 5 x 10(7) cycles under 3.6 MV/cm. Therefore, the HfAlOx film showed the great promise for integrating in high performance ferroelectric memory with thermal budget concerns.
Low power resistive random access memory using interface-engineered dielectric stack of SiOx/a-Si/TiOy with 1D1R-like structure
(2014-01-01)
Cheng, Chun-Hu
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Chou, K. I.
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Zheng, Zhi-Wei
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Hsu, Hsiao-Hsuan
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電子工程學系及電子研究所
In this study, we report a resistive random access memory (RRAM) using trilayer SiOx/a-Si/TiOy film structure. The low switching energy of <10 pJ, highly uniform current distribution (<13% variation), fast 50-ns speed and stable cycling endurance for 10(6) cycles are simultaneously achieved in this RRAM device. Such good performance can be ascribed to the use of interface-engineered dielectric stack with 1D1R-like structure. The SiOx tunnel barrier in contact with top Ni electrode to form diode-like rectifying element not only lowers self-compliance switching currents, but also improves cycling endurance, which is favorable for the application of high-density 3D memory. (C) 2013 Elsevier B. V. All rights reserved.
Ohmic contact on n-type Ge using Yb-germanide
(2012-11-26)
Zheng, Zhi-Wei
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Ku, Teng-Chieh
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Liu, Ming
;
Chin, Albert
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電子工程學系及電子研究所
Poor ohmic contact by Fermi-level pinning to valence band (EV) edge is one of the major challenges for germanium (Ge) n-type metal-oxide-semiconductor field-effect transistor (nMOSFET). Using low work-function rare-earth ytterbium (Yb), good ohmic contact on n-type Ge with alleviated Fermi-level pinning was demonstrated. Such ohmic behavior depends strongly on the germanide formation condition, where much degraded ohmic contact at 600 degrees C rapid thermal annealing is due to the lower Yb/Ge composition found by energy-dispersive x-ray spectroscopy. The ohmic behavior of Yb-germanide/n-type-Ge has high potential for future high-performance Ge nMOSFET application. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4768700]
P-type tin-oxide thin film transistors for blue-light detection application
(2016-12)
Chen, Po-Chun
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Chiu, Yu-Chien
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Zheng, Zhi-Wei
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Cheng, Chun-Hu
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Wu, Yung-Hsien
We reported the characteristics of p-type tin-oxide (SnO) thin film transistors (TFTs) upon illumination with visible light. Our p-type TFT device using the SnO film as the active channel layer exhibits high sensitivity toward the blue-light with a high light/dark read current ratio (I-light/I-dark) of 8.2 x 10(3) at a very low driven voltage of < 3 V. Since sensing of blue-light radiation is very critical to our eyes, the proposed p-type SnO TFTs with high sensitivity toward the blue-light show great potential for future blue-light detection applications. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
P-type tin-oxide thin film transistors for blue-light detection application
(2016-12)
Chen, Po-Chun
;
Chiu, Yu-Chien
;
Zheng, Zhi-Wei
;
Cheng, Chun-Hu
;
Wu, Yung-Hsien
We reported the characteristics of p-type tin-oxide (SnO) thin film transistors (TFTs) upon illumination with visible light. Our p-type TFT device using the SnO film as the active channel layer exhibits high sensitivity toward the blue-light with a high light/dark read current ratio (I-light/I-dark) of 8.2 x 10(3) at a very low driven voltage of < 3 V. Since sensing of blue-light radiation is very critical to our eyes, the proposed p-type SnO TFTs with high sensitivity toward the blue-light show great potential for future blue-light detection applications. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Performance Enhancements in p-Type Al-Doped Tin-Oxide Thin Film Transistors by Using Fluorine Plasma Treatment
(2017-02)
Chen, Po-Chun
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Chiu, Yu-Chien
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Liou, Guan-Lin
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Zheng, Zhi-Wei
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Cheng, Chun-Hu
This letter reports on a tin oxide (SnO) thin-film transistor (TFT) with p-type conduction that uses aluminum (Al) doping in the SnO active channel layer. Performance enhancements were further achieved by applying fluorine plasma treatment on the p-type Al-dopedSnO channel layer. The effects of the fluorine plasma treatment were also investigated. By tuning the power of the fluorine plasma treatment on the p-type Al-doped SnO channel layer, the optimal TFT device showed a very high on/off current ratio of 2.58x10(6) and a low threshold swing of 174 mV/decade, which could be attributed to the passivation effect of the plasma fluorination on the dominant donor-like traps at the SnO/HfO2 interface, as reflected by the suppression of the hysteresis phenomenon, the low density of interface traps, and the small subthreshold swing. The results indicate that the p-type Al-doped SnO TFT device with fluorine plasma treatment has considerable potential for application in future high-performance displays.
Stabilizing Ferroelectric Domain Switching of Hafnium Aluminum Oxide Using Metal Nitride Electrode Engineering
(2019-09-17)
Liu, Chien
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Tung, Yi-Chun
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Tseng, Chih-Yang
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Wang, Wei-Chun
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Chen, Hsuan-Han
In this work, we comprehensively investigated the metal-electrode stress engineering on HfAlO metal-ferroelectric-metal capacitor. According to experimental results, we confirm that high-nitrogen tantalum-nitride electrode with good chemical stability not only mitigates the anti-ferroelectric property and gate leakage current, but also improves the wake-up effect and endurance cycling characteristics, which shows the great potential for future applications of low-power ferroelectric memories. (c) 2019 The Electrochemical Society.