Browsing by Author "Huang, Chun-Yang"

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Compact Ga-Doped ZnO Nanorod Thin Film for Making High-Performance Transparent Resistive Switching Memory
(2014-10-01)
Huang, Chun-Yang
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Ho, Yen-Ting
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Hung, Chung-Jung
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Tseng, Tseung-Yuen
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材料科學與工程學系
Fully transparent and stable resistive switching characteristics in resistive random access memory (RRAM) device consisting of ITO/Ga doped ZnO (GZO)/ZnO/ITO architecture are proposed. The GZO nanorods with well aligned and extremely dense properties are considered as a thin film for RRAM device. The oxygen vacancies can be confined and migrate along grain boundaries in the GZO nanorod film. Therefore, the weakest point for formation and rupture of conductive filament can be limited at the interface between GZO nanorod film and ZnO seeding layer. Compared with ITO/ZnO/ITO device, a significant improvement in the distribution of high resistance state (HRS) and low resistance state (LRS) during resistance switching is demonstrated in the present device. In addition, a high endurance of more than 7000 cycles with the resistance ratios of HRS/LRS about 200 times is achieved in this device. The ITO/GZO/ZnO/ITO device is a good candidate for the transparent RRAM application.
Forming-free bipolar resistive switching in nonstoichiometric ceria films
(2014-01-27)
Ismail, Muhammad
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Huang, Chun-Yang
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Panda, Debashis
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Hung, Chung-Jung
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Tsai, Tsung-Ling
The mechanism of forming-free bipolar resistive switching in a Zr/CeO (x) /Pt device was investigated. High-resolution transmission electron microscopy and energy-dispersive spectroscopy analysis indicated the formation of a ZrO (y) layer at the Zr/CeO (x) interface. X-ray diffraction studies of CeO (x) films revealed that they consist of nano-polycrystals embedded in a disordered lattice. The observed resistive switching was suggested to be linked with the formation and rupture of conductive filaments constituted by oxygen vacancies in the CeO (x) film and in the nonstoichiometric ZrO (y) interfacial layer. X-ray photoelectron spectroscopy study confirmed the presence of oxygen vacancies in both of the said regions. In the low-resistance ON state, the electrical conduction was found to be of ohmic nature, while the high-resistance OFF state was governed by trap-controlled space charge-limited mechanism. The stable resistive switching behavior and long retention times with an acceptable resistance ratio enable the device for its application in future nonvolatile resistive random access memory (RRAM).
High-speed and localized resistive switching characteristics of double-layer SrZrO(3) memory devices
(2010-07-28)
Lin, Meng-Han
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Wu, Ming-Chi
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Huang, Chun-Yang
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
The fabrication of SrZrO(3) (SZO) memory devices with oxygen-rich (OR) and oxygen-deficient (OD) double layers, their resistive switching (RS) characteristics and mechanisms are investigated in this study. Due to the difference in oxygen content between the OR and OD layers formed by an oxygen flow control (OFC) process during SZO deposition, the RS region is effectively reduced and localized within the OR layer, which leads to a low operation voltage and stable RS behaviours. Furthermore, the OFC SZO device exhibits high-speed switching (10 ns) over 400 times and long retention (>10(6) s), showing promising potential for next-generation nonvolatile memory applications.
High-speed and localized resistive switching characteristics of double-layer SrZrO3 memory devices
(2010-07-28)
Lin, Meng-Han
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Wu, Ming-Chi
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Huang, Chun-Yang
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
The fabrication of SrZrO3 (SZO) memory devices with oxygen-rich (OR) and oxygen-deficient (OD) double layers, their resistive switching (RS) characteristics and mechanisms are investigated in this study. Due to the difference in oxygen content between the OR and OD layers formed by an oxygen flow control (OFC) process during SZO deposition, the RS region is effectively reduced and localized within the OR layer, which leads to a low operation voltage and stable RS behaviours. Furthermore, the OFC SZO device exhibits high-speed switching (10 ns) over 400 times and long retention (>10(6) s), showing promising potential for next-generation nonvolatile memory applications.
Improved Resistive Switching Characteristics by Al2O3 Layers Inclusion in HfO2-Based RRAM Devices
(2013)
Huang, Chun-Yang
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Jieng, Jheng-Hong
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Jang, Wen-Yueh
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
A series of complex HfO2/Al2O3 layer by layer resistive random access memory(RRAM) structure grown by atomic layer deposition are investigated. The modulation of forming voltage can be achieved by controlling the number of Al2O3 layers in HfO2 devices. In addition, the crystallization temperature of HfO2 based RRAM devices can also be improved by insetting Al2O3 layers in HfO2 film. Compared with pure HfO2 device, a significant improvement in resistive switching properties such as forming voltage variation and the distribution of HRS/LRS during resistance switching is demonstrated in the HfO2/Al2O3 layer by layer devices. Moreover, good endurance characteristic and highly reliable multibit operation are also achieved in this device structure. (c) 2013 The Electrochemical Society. All rights reserved.
Investigation of thermal stability and reliability of HfO2 based resistive random access memory devices with cross-bar structure
(2015-05-14)
Chand, Umesh
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Huang, Kuan-Chang
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Huang, Chun-Yang
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Ho, Chia-Hua
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Lin, Chen-Hsi
The effect of the annealing treatment of a HfO2 resistive switching layer and the memory performance of a HfO2-based resistive random access memory (cross-bar structure) device were investigated. Oxygen is released from HfO2 resistive switching layers during vacuum annealing, leading to unstable resistive switching properties. This oxygen release problem can be suppressed by inserting an Al2O3 thin film, which has a lower Gibbs free energy, between the HfO2 layer and top electrode to form a Ti/Al2O3/HfO2/TiN structure. This device structure exhibited good reliability after high temperature vacuum annealing and post metal annealing (PMA) treatments. Moreover, the endurance and retention properties of the device were also improved after the PMA treatment. (c) 2015 AIP Publishing LLC.
Mechanism of High Temperature Retention Property (up to 200 degrees C) in ZrO2-Based Memory Device With Inserting a ZnO Thin Layer
(2014-10-01)
Chand, Umesh
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Huang, Chun-Yang
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Tseng, Tseung-Yuen
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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
In this letter, the switching mechanism of the ZrO2-based RRAM devices with the uniform and reliable reliability properties is investigated. The stability of memory window can be improved by inserting a ZnO thin film with the nonstoichiometric property between Ti top electrode and ZrO2 layer. Compared with ZrO2 film, the ZnO one can easily perform the oxidation-reduction reaction for stable endurance properties. In addition, through Gibbs free energy comparison of TiOx, ZrO2, and ZnO, we can demonstrate that the Gibbs free energy contributes to the retention performance. The device with thin ZnO layer has stable retention performance at high temperature (200 degrees C) due to its higher Gibbs free energy value than TiOx.
Mechanism of Nonlinear Switching in HfO2-Based Crossbar RRAM With Inserting Large Bandgap Tunneling Barrier Layer
(2015-11-01)
Chand, Umesh
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Huang, Kuan-Chang
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Huang, Chun-Yang
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
In this paper, the nonlinear switching mechanism of the Ti/HfO2/Al2O3/TiN crossbar structure resistive random access memory device with good reliability is investigated. The nonlinearity of the device can be revealed by inserting a large bandgap of an Al2O3 thin layer between the TiN bottom electrode and the HfO2 switching film. The nonlinear switching mechanism caused by Flower-Nordheim tunneling involves the tunneling barrier of the Al2O3 layer. Besides, the nonlinear behavior is also sensitive to the thickness of the inserting Al2O3 layer. A high nonlinear factor of 37, large endurance more than 10(4), and good retention properties are achieved in the Ti/HfO2/Al2O3 (1-nm)/TiN structure.
Metal induced crystallized poly-Si-based conductive bridge resistive switching memory device with one transistor and one resistor architecture
(2015-11-16)
Chand, Umesh
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Huang, Chun-Yang
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Kumar, Dayanand
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
In this letter, the metal induced crystallization (MIC) process is used in the Si-based conductive bridging resistive random access memory (CBRAM) application. The amorphous Si (a-Si) is transformed to crystallized poly-silicon (poly-Si) at a low temperature by using Ni metal for inducing poly-Si to provide the resistive switching. The MIC process can produce a highly preferred orientation poly-Si film, which can create the exact paths or grain boundaries through the top and down electrodes in the present CBRAM device. The grain boundary in MIC poly-Si layer can confine the conductive filament of metal bridging growth in it, which can improve the switching fluctuation behavior in the nonvolatile memory application. Compared with the a-Si based device, a significant improvement in terms of resistive switching parameters such as stability and resistance distribution is demonstrated in the MIC poly-Si CBRAM device. Moreover, the well-behaved memory performance, such as high ON/OFF resistance ratio (4 order), a large AC endurance (10(6)), and good retention characteristics (10(4) s at 125 degrees C) are achieved in the Cu/poly-Si/n(+)-Si CMOS compatible cross bar structure. (c) 2015 AIP Publishing LLC.
Resistive switching characteristics of nickel silicide layer embedded HfO2 film
(2012-03-12)
Panda, Debashis
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Huang, Chun-Yang
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Tseng, Tseung-Yuen
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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
Resistive switching behavior of the Ti/HfO2:NiSi:HfO2/Pt memory structure is investigated. Auger electron spectroscopy analysis indicates no metal diffusion from the electrodes and silicide layer on high-k film. Cross-sectional transmission electron microscopic micrographs revealed the thicknesses of the HfO2 and silicide layer. Significant decrease of forming voltage is observed for the 550 degrees C, 1 min annealed device embedded with nickel silicide (NiSi) layers. Entire device shows bipolar switching properties with very low set/reset voltage. The optimized annealed device with NiSi embedded layer exhibits improved memory performances such as good on/off ratio (>10(2)), long retention more than 10(4)s, and reasonable endurance (>10(3) cycles). A conducting filament model based on two stacks structure is employed to well explain the switching behaviors. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3694045]
Resistive switching characteristics of Pt/CeOx/TiN memory device
(2014-06-01)
Ismail, Muhammad
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Talib, Ijaz
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Huang, Chun-Yang
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Hung, Chung-Jung
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Tsai, Tsung-Ling
The resistive switching characteristics of Pt/CeOx/TiN memory devices are investigated for potential applications in nonvolatile resistive random access memory (RRAM). The X-ray diffraction characteristics of the sputtered CeOx layer indicate the formation of nanocrystalline single-phase CeO2 with a cubic fluorite structure. The existence of oxygen vacancies in the Pt/CeOx/TiN memory device was determined by X-ray photoelectron spectroscopic studies, while the presence of an interfacial layer between CeOx and the TiN bottom electrode was investigated by Xray diffraction and high resolution transmission electron microscopy. The TiON layer formed at the TiN/CeOx interface seems to play a key role in the resistive switching mechanism of the device. The present CeOx-based device shows excellent bipolar resistive switching characteristics, including a low operation current (100 mu A), high ON/OFF resistance ratio (similar to 10(5)), and good retention/stress characteristics at both room temperature and 85 degrees C. (C) 2014 The Japan Society of Applied Physics
STABLE RESISTIVE SWITCHING CHARACTERISTICS OF Al2O3 LAYERS INSERTED IN HfPO2 BASED RRAM DEVICES
(2014-01-01)
Huang, Chun-Yang
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Jieng, Jheng-Hong
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Tseng, Tseung-Yuen
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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
Resistive switching random access memory (RRAM) has attracted extensive attention for next-generation nonvolatile memory application due to the merits of low power consumption, high speed operation, and high density integration. The resistive switching (RS) characteristics of various metal oxides have been studied. Among those materials, HfO2 is one of the appealing materials that had received considerable attention owing to a high dielectric constant, simple composition, and its standard CMOS processes compatibility. However, the thermal stability of HfO2 thin film is a serious issue for memory characteristics due to the low crystalline temperature. In this work, we utilized ALD growth HfO2 thin films with inserted different amount of Al2O3 layers as RS layer for crystallization and RS characteristics study. From the experimental results, the crystalline temperatures depend on the amount of inserted Al2O3 layers. By the way, the forming voltages were modulated by using different amount of Al2O3 layers inserted in HfO2 thin film, changed from 2.5 V (HfO2) to 4.1 V (Al2O3). Moreover, the device shows better resistive switching performance than pure HfO2 and pure Al2O3 devices, such as more stable operation voltage and higher resistive switching cycles (11000 cycles)
Suppression of endurance degradation by utilizing oxygen plasma treatment in HfO2 resistive switching memory
(2015-04-13)
Chand, Umesh
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Huang, Chun-Yang
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Jieng, Jheng-Hong
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Jang, Wen-Yueh
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Lin, Chen-Hsi
Based on the phenomenon of endurance degradation problem caused by no sufficient oxygen ions for resistive switching, we use the oxygen plasma treatment in HfO2 layer to increase the extra available oxygen ions in resistive random access memory devices. To avoid the Ti top electrode directly absorbing the additional oxygen ions from HfO2 layer with oxygen plasma treatment, a thin HfO2 film is inserted to separate them. Therefore, the endurance degradation can be suppressed in the present structure. High speed (30 ns) and large endurance cycles (up to 10(10) cycles) are achieved in this device structure for next generation nonvolatile memory application. (C) 2015 AIP Publishing LLC.
Switching mechanism of double forming process phenomenon in ZrOx/HfOy bilayer resistive switching memory structure with large endurance
(2014-02-10)
Huang, Chun-Yang
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Huang, Chung-Yu
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Tsai, Tsung-Ling
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Lin, Chun-An
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Tseng, Tseung-Yuen
In this Letter, the mechanism of double forming process phenomenon revealing in ZrO2/HfO2 bilayer resistive random access memory structure is investigated. This phenomenon caused by the formation of TiON interfacial layer can be well explained by using the energy band diagram. The TiON interfacial layer will be a tunneling barrier during the first forming process when a negative voltage applied on the device, while it will breakdown when applying a positive voltage. Besides, due to the double forming process, an asymmetric conductive filament with narrower size at ZrO2/HfO2 interface is formed in the device. The point for formation and rupture of the conductive filament can be confined at the ZrO2/HfO2 interface, and it will suppress the consumption of oxygen ions during endurance test. Therefore, high speed (40 ns) and large endurance (10(7) cycles) characteristics are achieved in this device structure. (C) 2014 AIP Publishing LLC.