• Title/Summary/Keyword: Chalcogenide memory

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Field-induced Resistive Switching in Ge25Se75 Based ReRAM

  • Kim, Jang-Han;Nam, Gi-Hyeon;Jeong, Hong-Bae
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.02a
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    • pp.413-414
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    • 2012
  • Programmable Metallization Cell (PMC) memory, which utilizes electrochemical control of nanoscale quantities of metal in thin films of solid electrolyte, shows great promise as a future solid state memory. The technology utilizes the electrochemical formation and removal of metallic pathways in thin films of solid electrolyte. Key attributes are low voltage and current operation, excellent scalability, and a simple fabrication sequence. In this study, we investigated the nature of thin films formed by photo doping of Ag+ ions into chalcogenide materials for use in solid electrolyte of programmable metallization cell devices. We measured the I-V characteristics by field-effect of the device. The results imply that a Ag-rich phase separates owing to the reaction of Ag with free atoms from chalcogenide materials.

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The Phase Transition with Electric Field in Ternary Chalcogenide Thin Films

  • Yang, Sung-Jun;Lee, Jae-Min;Shin, Kyung;Chung, Hong-Bay
    • Transactions on Electrical and Electronic Materials
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    • v.5 no.5
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    • pp.185-188
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    • 2004
  • Phase transitions from the amorphous to crystalline states, and vice versa, of GST(GeSbTe) and AST(AsSbTe) thin films by applying electrical pulses have been studied. These materials can be used as nonvolatile memory devices. The thickness of ternary chalcogenide thin films is approximately 100 nm. Upper and lower electrodes were made of AI. I-V characteristics after impressing the variable pulses to GST and AST films. Tc(crystallization temperature) of AST system is lower than that of the GST system, so that the current pulse width of crystallization process can be decreased.

The Study on Characteristic of Phase Transition in differential Chalcogenide Thin Films ($Se_1Sb_2Te_2$ 칼코게나이드 박막의 두께에 따른 상변화 특성 연구)

  • Lee, Jae-Min;Yang, Sung-Jun;Shin, Kyung;Chung, Hong-Bay;Kim, Young-Hae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.340-343
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    • 2004
  • The phase transition between amorphous and crystalline states in chalcogenide semiconductor films can controlled by electric pulses or pulsed laser hem: hence some chalcogenide semiconductor films can be applied to electrically write/erase nonvolatile memory devices, where the low conductive amorphous state and the high conductive crystalline state are assigned to binary states. This letters researched into the characteristic of phase change transition in differential Chalcogenide thin films materials. The electrode used Al and experimented on 100nm, 300nm, 500nm respectively.

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Electrical characteristic of differential ternary chalcogenide thin films (칼코게나이드 3원계 박막에서의 전기적 특성에 관한 연구)

  • Yang, Sung-Jun;Shin, Kyung;Lee, Jae-Min;Chung, Hong-Bay
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.377-380
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    • 2004
  • The phase transition between amorphous and crystalline states in chalcogenide semiconductor films can controlled by electric pulses or pulsed laser beam; hence some chalcogenide semiconductor films can be applied to electrically write/erase nonvolatile memory devices, where the low conductive amorphous state and the high conductive crystalline state are assigned to binary states. GeSbTe(GST), AsSbTe(AST), SeSbTe(SST) used to phase change materials by appling electrical pulses. Thickness of ternary chalcogenide thin films have about 100nm. Upper and lower electrode were made of Al. It is compared with I-V characteristics after impress the variable pulses.

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Electrical Characteristics of and Temperature Distribution in Chalcogenide Phase Change Memory Devices Having a Self-Aligned Structure (자기정렬구조를 갖는 칼코겐화물 상변화 메모리 소자의 전기적 특성 및 온도 분포)

  • Yoon, Hye Ryeon;Park, Young Sam;Lee, Seung-Yun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.6
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    • pp.448-453
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    • 2019
  • This work reports the electrical characteristics of and temperature distribution in chalcogenide phase change memory (PCM) devices that have a self-aligned structure. GST (Ge-Sb-Te) chalcogenide alloy films were formed in a self-aligned manner by interdiffusion between sputter-deposited Ge and $Sb_2Te_3$ films during thermal annealing. A transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) analysis demonstrated that the local composition of the GST alloy differed significantly and that a $Ge_2Sb_2Te_5$ intermediate layer was formed near the $Ge/Sb_2Te_3$ interface. The programming current and threshold switching voltage of the PCM device were much smaller than those of a control device; this implies that a phase transition occurred only in the $Ge_2Sb_2Te_5$ intermediate layer and not in the entire thickness of the GST alloy. It was confirmed by computer simulation, that the localized phase transition and heat loss suppression of the GST alloy promoted a temperature rise in the PCM device.

Resistive Memory Switching in Ge5Se5 Thin Films

  • Kim, Jang-Han;Hwang, Yeong-Hyeon;Chung, Hong-Bay
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.326-326
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    • 2014
  • It has been known since the mid 1960s that Ag can be photodissolved in chalcogenide glasses to form materials with interesting technological properties. In the 40 years since, this effect has been used in diverse applications such as the fabrication of relief images in optical elements, micro photolithographic schemes, and for direct imaging by photoinduced Ag surface deposition. ReRAM, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of a conductive filament in a solid electrolyte. Especially, Ag-doped chalcogenide glasses and thin films have become attractive materials for fundamental research of their structure, properties, and preparation. Ag-doped chalcogenide glasses have been used in the formation of solid electrolyte which is the active medium in ReRAM devices. In this paper, we investigated the nature of thin films formed by the photo-dissolution of Ag into Ge-Se glasses for use in ReRAM devices. These devices rely on ion transport in the film so produced to create electrically programmable resistance states [1-3]. We have demonstrated functionalities of Ag doped chalcogenide glasses based on their capabilities as solid electrolytes. Formation of such amorphous systems by the introduction of Ag+ ions photo-induced diffusion in thin chalcogenide films is considered. The influence of Ag+ ions is regarded in terms of diffusion kinetics and Ag saturation is related to the composition of the hosting material. Saturated Ag+ ions have been used in the formation of conductive filaments at the solid electrolyte which is the active medium in ReRAM devices. Following fabrication, the cell displays a metal-insulator-metal structure. We measured the I-V characteristics of a cell, similar results were obtained with different via sizes, due to the filamentary nature of resistance switching in ReRAM cell. As the voltage is swept from 0 V to a positive top electrode voltage, the device switches from a high resistive to a low resistive, or set. The low conducting, or reset, state can be restored by means of a negative voltage sweep where the switch-off of the device usually occurs.

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A high performance nonvolatile memory cell with phase change material of $Ge_1Se_1Te_2$ ($Ge_1Se_1Te_2$ 상변화 재료를 이용한 고성능 비휘발성 메모리에 대한 연구)

  • Lee, Jae-Min;Shin, Kyung;Chung, Hong-Bay
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.15-16
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    • 2005
  • Chalcogenide phase change memory has high performance to be next generation memory, because it is a nonvolatile memory processing high programming speed, low programming voltage, high sensing margin, low consumption and long cycle duration. We have developed a new material of PRAM with $Ge_1Se_1Te_2$. This material has been propose to solve the high energy consumption and high programming current. We have investigated the phase transition behaviors in function of various process factor including contact size, cell size, and annealing time. As a result, we have observed that programming voltage and writing current of $Ge_1Se_1Te_2$ are more improved than $Ge_2Sb_2Te_5$ material.

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Resistive Switching Characteristics of Ag Doped Ge0.5Se0.5 Solid Electrolyte

  • Kim, Jang-Han;Nam, Ki-Hyun;Chung, Hong-Bay
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.478-478
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    • 2013
  • Resistance-change Random Access Memory (ReRAM) memory, which utilizes electrochemical control of metal in thin films of solid electrolyte, shows great promise as a future solid state memory. The technology utilizes the electrochemical formation and removal of metallic pathways in thin films of solid electrolyte. Key attributes are low voltage and current operation, excellent scalability, and a simple fabrication sequence. In this work, we investigated the nature of thin films formed by photo doping of Ag+ ions into chalcogenide materials for use in solid electrolyte of Resistance-change RAM devices and switching characteristics.

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Electrical characteristic of Phase-change Random Access Memory with improved bottom electrode structure (하부전극 구조 개선에 의한 상변화 메모리의 전기적 특성)

  • Kim, Hyun-Koo;Choi, Hyuk;Cho, Won-Ju;Chung, Hong-Bay
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.69-70
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    • 2006
  • A detailed Investigation of cell structure and electrical characteristic in chalcogenide-based phase-change random access memory(PRAM) devices is presented. We used compound of Ge-Sb-Te material for phase-change cell. A novel bottom electrode structure and manufacture are described. We used heat radiator structure for improved reset characteristic. A resistance change measurement is performed on the test chip. From the resistance change, we could observe faster reset characteristic.

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Field-induced Resistive Switching in Ge25Se75-based ReRAM Device (Ge25Se75-based ReRAM 소자의 전계에 의한 저항 변화에 대한 연구)

  • Kim, Jang-Han;Nam, Ki-Hyun;Chung, Hong-Bay
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.3
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    • pp.182-186
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    • 2012
  • Resistance-change Random Access Memory(ReRAM) memory, which utilizes electrochemical control of metal in thin films of solid electrolyte, shows great promise as a future solid state memory. The technology utilizes the electrochemical formation and removal of metallic pathways in thin films of solid electrolyte. Key attributes are low voltage and current operation, excellent scalability, and a simple fabrication sequence. In this work, we investigated the nature of thin films formed by photo doping of $Ag^+$ ions into chalcogenide materials for use in solid electrolyte of Resistance-change RAM devices and switching characteristics according to field-effect.