Browsing by Author "Tseng, T. Y."

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Current status of resistive nonvolatile memories
(2008-12-01)
Lin, Chih-Yang
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Liu, Chih-Yi
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Lin, Chun-Chieh
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Tseng, T. Y.
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電子工程學系及電子研究所
Several emerging nonvolatile memories (NVMs) such as ferroelectric memory, magnetoresistive rams and ovonic universal memory are being developed for possible applications. Resistive random access memory (RRAM) is another interesting competitor in the class of NVMs. The RRAM is based on a large change in electrical resistance when the memory film is exposed to voltage or current pulses, and can keep high or low resistance states without any power. The ideal RRAM Should have the superior properties of reversible switching, long retention tune, multilevel switching, simple structure, small size, and low operating voltage. Perovskite oxides, transition metal oxides, and molecular materials were found to have resistive memory properties. This presentation reviews the ongoing research and development activities on future resistance NVMs technologies incorporating these new memory materials. The possible basic mechanisms for their bistable resistance switching are described. The effect of processing, composition, and structure on the properties of resistive memory materials and consequently the devices are discussed.
Device Instability of ReRAM and a Novel Reference Cell Design for Wide Temperature Range Operation
(2017-09-01)
Lin, Y. H.
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Lin, Y. Y.
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Lee, F. M.
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Ho, Y. H.
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Hsu, K. C.
This letter addresses two difficult challenges for transition metal oxide resistive random access memories (ReRAMs)-sensitivity to operation temperature and random fluctuation of resistance value. A careful study of a WOx ReRAM array reveals that these devices are unstable and their read currents fluctuate with time due to random telegraph noise and structure relaxation. Consequently, even after careful programming, the current distribution can broaden with time and tail bit population grows. Furthermore, ReRAM state is sensitive to temperature and a reference cell made of the same device material must be used. Thus, although the broadening of read current distribution may be tolerated by creating a larger RESET/SET memory window, the current fluctuation still makes it impossible to predict the output of the reference cell, leading to array malfunction. This letter investigates the current (resistance) instability in detail and proposes a reference array with a novel trimming method that can stabilize the reference current level. The proposed reference array has very good dc stress reliability as well as wide-range temperature tracking performance from -40 degrees C to 85 degrees C.
Effect of alumina doping on structural, electrical, and optical properties of sputtered ZnO thin films
(2006-11-25)
Bai, S. N.
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Tseng, T. Y.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
A systematic study of the influence of alumina (Al2O3) doping on the optical, electrical, and structural characteristics of sputtered ZnO thin films is reported in this study. The ZnO thin films were prepared on 1737F Coming glass substrates by R.F. magnetron sputtering from a ZnO target mixed with Al2O3 of 0-4 wt.%. X-ray diffraction (XRD) analysis demonstrates that the ZnO thin films with Al2O3 of 0-4 wt.% have a highly (002) preferred orientation with only one intense diffraction peak with a full width at half maximum (FWEM) less than 0.5 degrees. The electrical properties of the Al2O3-doped ZnO thin films appear to be strongly dependent on the Al2O3 concentration. The resistivity of the films decreases from 74 Omega(.)cm to 2.2 x 10(-3) Omega(.)cm as the Al2O3 content increases from 0 to 4 wt.%. The optical transmittance of the Al2O3-doped ZnO thin films is studied as a function of wavelength in the range 200-800 nm. It exhibits high transparency in the visible-NIR wavelength region with some interference fringes and sharp ultraviolet absorption edges. The optical bandgap of the Al2O3-doped ZnO thin films show a short-wavelength shift with increasing of Al2O3 content. (c) 2006 Elsevier B.V. All rights reserved.
High Performance Resistive Switching Characteristics of SiN Films with a Cu/Ta/SiN/Cu/SiN/TiN Multilayer Structure
(2017-01-01)
Kumar, D.
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Tseng, T. Y.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The bipolar resistive switching properties of SiN based conductive bridge random access memory (CBRAM) device are investigated for non-volatile memory applications in a Cu/Ta/SiN/Cu/SiN/TiN multilayer structure. The device shows good switching characteristics with set voltages between 0.8 V and 1.3 V and reset voltages between -0.3 V and -0.7 V with a variation of less than 0.1 V. The Cu/Ta/SiN/Cu/SiN/TiN multilayer CBRAM device exhibits excellent memory performance, such as long stable endurance cycles (> 4.5x10(3)) during the test without any degradation, good retention ability (> 10(4) s) at a temperature of 120 C-degrees with more than 10(2) on/off resistance ratio.
Metal oxide resistive switching memory: Materials, properties and switching mechanisms
(2017-01-01)
Kumar, D.
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Aluguri, R.
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Chand, U.
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Tseng, T. Y.
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電子工程學系及電子研究所
With the continuously changing landscape of the computer technologies, a new memory type is needed that will be fast, energy efficient and long-lasting. It shall combine the speed of random access memory (RAM) and nonvolatile in the same time. Resistive RAM (RRAM) is one of the most promising candidates in this respect. RRAM has attracted a great deal of attention owing to its potential as a possible replacement for flash memory in next-generation nonvolatile memory (NVM) applications. A brief summary of binary metal oxide RRAM is given in this review. We discuss the RRAM technology development based on published papers, including the mechanism of resistive switching in transition metal oxides, resistive switching materials, device structure, properties, and reliability such as endurance and retention of the device. We also provide possible solutions through innovations in device materials, structures, and understanding the device physics.
Microstructures and electrical properties of lead-based PBZNZT and lead-free BNKT piezoelectric ceramics using microwave sintering
(2011-05-01)
Chen, P. Y.
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Chen, C. S.
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Chou, C. C.
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Tseng, T. Y.
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Chen, H. D.
This paper is a comparative study involving sintering conditions (different sintering temperatures and time), process (conventional and microwave sintering), microstructures, and electrical measurements to investigate the mechanism of microwave absorption, and the difference in the microstructural characteristics and electrical properties of lead-based and lead-free ceramics. The lead-based piezoelectric ceramics are x(0.94PbZn(1/3)Nb(2/3)O(3) + 0.06BaTiO(3)) + (1 - x) PbZr(y)Ti(1) (y)O(3) where x = 0.5, y = 0.52 (abbreviated as PBZNZT) and the lead-free ceramics are (Bi(0.5)(Na(1-x)K(x))(0.5))TiO(3) where x = 0.18 (abbreviated as BNKT), all sintered by microwave heating. Experimental results indicate that PBZNZT and BNKT specimens have different microwave absorption efficiencies. Compared with BNKT samples, PBZNZT samples absorb microwave radiation more efficiently in MWS process. This might be attributed to the contribution of the dielectric constant and dipole loss which might dominate the absorption of microwave energy for ferroelectric and piezoelectric materials. HRTEM and energy dispersive spectroscopic investigations show that the grain boundaries of MWS samples exhibit less PbO and ZnO segregation than those of CS samples form PBZNZT specimens. On the other hand, BNKT specimens exhibit no compositional segregation at the grain boundaries after the CS and MWS processes. In addition, the MWS process can achieve a more uniform composition and crystallization in PBZNZT and BNKT ceramics, thus improving the electrical properties. (C) 2011 Elsevier B.V. All rights reserved.
One bipolar transistor selector - One resistive random access memory device for cross bar memory array
(2017-09-01)
Aluguri, R.
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Kumar, D.
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Simanjuntak, F. M.
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Tseng, T. Y.
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電子工程學系及電子研究所
Abipolar transistor selector was connected in series with a resistive switching memory device to study its memory characteristics for its application in cross bar array memory. The metal oxide based p-n-p bipolar transistor selector indicated good selectivity of about 10(4) with high retention and long endurance showing its usefulness in cross bar RRAM devices. Zener tunneling is found to be the main conduction phenomena for obtaining high selectivity. 1BT-1R device demonstrated good memory characteristics with non-linearity of 2 orders, selectivity of about 2 orders and long retention characteristics of more than 10(5) sec. One bit-line pull-up scheme shows that a 650 kb cross bar array made with this 1BT1R devices works well with more than 10 % read margin proving its ability in future memory technology application. (C) 2017 Author(s).
One-Dimensional ZnO Nanostructures
(2012-06-01)
Jayadevan, K. P.
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Tseng, T. Y.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The wide-gap semiconductor ZnO with nanostructures such as nanoparticle, nanorod, nanowire, nanobelt, nanotube has high potential for a variety of applications. This article reviews the fundamentals of one-dimensional ZnO nanostructures, including processing, structure, property, application and their processing-microstructure-property correlation. Various fabrication methods of the ZnO nanostructures including vapor-liquid-solid process, vapor-solid growth, solution growth, solvothermal growth, template-assisted growth and self-assembly are introduced. The characterization and properties of the ZnO nanostructures are described. The possible applications of these nanostructures are also discussed.
Optical Properties of Ce-Doped ZnO Nanowires Directionally Grown by Hydrothermal Method
(2008-09-01)
Chen, Y. S.
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Tseng, T. Y.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Well directionally grown Ce-doped ZnO nanowires were successfully synthesized by a simple hydrothermal method. The Ce dopant plays a key role in evolving the morphology, affecting the crystalline size, and forming the uniform nanostructure of the ZnO nanowires. The amount of Ce dopant in the ZnO nanowires also affects the regions of blue-shift in the UV and green emission peaks and the intensities of emission peaks based on the cathodoluminescence spectra of the nanowires. Moreover, the effect of Ce doping amount on the microstructure of the nanowires is also presented.
Preparation and Characterizations of ZnO Nanotubes by Acidic Etching Nanowires
(2008-09-01)
Yao, C. Y.
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Chen, G. J.
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Tseng, T. Y.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Single crystalline ZnO nanowires were synthesized by hydrothermal process and then formed nanotubes by acidic etching these nanowires in acetic solution at 85 degrees C. The nanotube diameter can be easily controlled by dividing the nanowires growth and etching process. The ZnO nanotubes remain single crystalline hexagonal structure after the etching process. The defects existed in the nanowires and the dangling bonds of the nanowires' surface play the important roles for the etching process. An etching model for forming ZnO nanotubes is proposed, which can be proved by our experimental results.
Structural and optical properties of Al-doped ZnO nanowires synthesized by hydrothermal method
(2007-12-03)
Bai, S. N.
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Tsai, H. H.
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Tseng, T. Y.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The growth of one dimensional Al-doped ZnO nanowires on a silicon substrate with a ZnO seeding layer by using a low temperature hydrothermal method is demonstrated. The structural and optical characteristics of the solution-grown Al-doped ZnO nanowires were studied using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and cathodoluminescence (CL) measurements. The FE-SEM images show that the ZnO nanowires are hexagonal column shaped and stand perpendicularly on the silicon substrate. It is found in XRD patterns that the ZnO nanowires annealed at various temperatures are all wurtzite crystal structure and have (002) preferred orientation. As the annealing temperature changed, the intensity of (100) and (10 1) peaks reveals distinct change. The CL spectra show the as-grown ZnO nanowires display a weak and narrow UVemission centered at 376 nm. A strong and very broad green-yellow emission band with a center at 575 nm as well as a shoulder like orange-red emission band centering at 625 nm is also demonstrated. It is shown that the luminescence intensity centered at 376 nm increased, the shoulder like emission centered at 625 nm decreased but emission centered at 575 nm disappeared after thermal annealing treatment in oxygen atmosphere. (C) 2007 Elsevier B.V. All rights reserved.
Switching and synaptic characteristics of AZO/ZnO/ITO valence change memory device
(2019-01-01)
Simanjuntak, F. M.
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Chandrasekaran, S.
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Gapsari, F.
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Tseng, T. Y.
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材料科學與工程學系
This paper reports the resistive switching and synaptic capability of AZO/ZnO/ITO transparent and flexiblevalence change memory device structure. The device performs stable endurance for more than 50 cycles with sufficient ON/OFF ratio of one order of magnitude; no intermediate state (data error) is observed during the cycle-to-cycle test. By exploiting the analog switching characteristic of the device and employing identical pulses to the top electrode, a synaptic behavior can be achieved. A low programming voltage of 1.5V is used to modulate the conductance during potentiation and depression which indicate that the device is a logic-compatible. The conduction mechanism during the switching processand the device performance is discussed.
USING DECISION ANALYSIS METHOD TO EVALUATE THE EFFECTIVENESS OF SIMILAR FUNCTION MEDICAL MATERIALS IN HOSPITAL
(2012-11-01)
Fang, N. C.
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Yao, M. J.
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Tseng, T. Y.
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交大名義發表
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National Chiao Tung University
USING DECISION ANALYSIS METHOD TO EVALUATE THE EFFECTIVENESS OF SIMILAR FUNCTION MEDICAL MATERIALS IN HOSPITAL
(2012-11-01)
Fang, N. C.
;
Yao, M. J.
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Tseng, T. Y.
;
交大名義發表
;
National Chiao Tung University
USING DECISION ANALYSIS METHOD TO EVALUATE THE EFFECTIVENESS OF SIMILAR FUNCTION MEDICAL MATERIALS IN HOSPITAL
(2012-11-01)
Fang, N. C.
;
Yao, M. J.
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Tseng, T. Y.
;
交大名義發表
;
National Chiao Tung University