Amorphization Optimization of Ge2Sb2Te5 Media for Electrical Probe Memory Applications

Wang, Lei; Yang, Cihui; Wen, Jing; Xiong, Bangshu

doi:10.3390/nano8060368

Cited by 6 publications

(5 citation statements)

References 23 publications

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“…The formed crystalline region (i.e., χ = 1) in this case is determined by the calculated crystal volume fraction at each mesh grid from Equation (), whereas the region with the temperature and cooling rate reaching ≈893 K and ≈−37 °C ns −1 , respectively, is considered as amorphized. [ 46 ] In this case, the calculated crystal and amorphization fraction at each mesh grid drastically depend on the resulting temperature inside the GST layer. The thermal conductivity (K GST ) and the refractive index of the GST mesh grid (n GST +ik GST ) were described as a function of the crystal fraction, defined as

K_{GST} = K_{cryst} \cdot χ + K_{am} \cdot (1 - χ)

n_{GST} = n_{cryst} \cdot χ + n_{am} \cdot (1 - χ)

k_{GST} = k_{cryst} \cdot χ + k_{am} \cdot (1 - χ)

where K cryst and K am are the thermal conductivity of the GST in the crystalline and amorphous phase, respectively; n cryst and n am are the real parts of the refractive index of the GST media at 1550 nm in crystalline and amorphous phases, respectively; k cryst and k am are the imaginary parts of the refractive index of the GST media at 1550 nm in crystalline and amorphous phases, respectively.…”

Section: Methodsmentioning

confidence: 99%

Design of Phase‐Change Memory Using Apertureless Scanning Near‐Field Optical Microscopy in the Near‐Infrared Region

Liu

Wang

2020

Physica Rapid Research Ltrs

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A novel optical secondary storage memory operated in the near‐infrared (NIR) region is developed through the integration of an apertureless scanning near‐field optical microscopy probe with the conventional Ge2Sb2Te5 storage stack. The probe composite and the optical coefficients of the storage media stack, particularly for the indium tin oxide capping layer, are optimized according to a previously developed electromagnetic wave model, and a newly established density functional theory model, respectively. The dielectric core and the metal coating medium of the probe are devised to be glass and barium, respectively, to provide high electric field in the NIR region, while the thickness of the ITO capping layer is chosen to be 3 nm here to provide high optical transmittance simultaneously with exemption of complex fabrication process. The recording operation of the aforementioned optimized device is subsequently simulated by a newly established thermo‐optics model, and its feasibility of achieving ≥Tbit in−2, 108 bits per second, and picojoule energy consumption per bit is theoretically demonstrated.

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K_{GST} = K_{cryst} \cdot χ + K_{am} \cdot (1 - χ)

n_{GST} = n_{cryst} \cdot χ + n_{am} \cdot (1 - χ)

k_{GST} = k_{cryst} \cdot χ + k_{am} \cdot (1 - χ)

Section: Methodsmentioning

confidence: 99%

Design of Phase‐Change Memory Using Apertureless Scanning Near‐Field Optical Microscopy in the Near‐Infrared Region

Liu

Wang

2020

Physica Rapid Research Ltrs

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“…Later Wright’s model was expanded to three dimensions (3D) by Wang et al [ 48 , 49 , 50 ], who also introduced more physically realistic material properties (e.g., the thermal conductivity of the DLC media) and some important electrical/thermal behaviors previously ignored by Wright (e.g., threshold switching and electrical/thermal boundary resistance) into the improved model. This resulted in a newly optimized architecture composed of a SiO 2 encapsulated probe and a media stack consisting of 2 nm DLC capping with an electrical conductivity of 50 Ω −1 ⋅m −1 and a thermal conductivity of 0.5 W⋅m −1 ⋅K −1 , a 10 nm GST layer, and a 40 nm TiN bottom with an electrical conductivity of 5 × 10 6 Ω −1 ⋅m −1 and thermal conductivity of 12 W⋅m −1 ⋅K −1 .…”

Section: Current Status Of Phase-change Electrical Probe Memorymentioning

confidence: 99%

Overview of Phase-Change Electrical Probe Memory

Wang

Ren²,

Wen

et al. 2018

Nanomaterials

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Phase-change electrical probe memory has recently attained considerable attention owing to its profound potential for next-generation mass and archival storage devices. To encourage more talented researchers to enter this field and thereby advance this technology, this paper first introduces approaches to induce the phase transformation of chalcogenide alloy by probe tip, considered as the root of phase-change electrical probe memory. Subsequently the design rule of an optimized architecture of phase-change electrical probe memory is proposed based on a previously developed electrothermal and phase kinetic model, followed by a summary of the state-of-the-art phase-change electrical probe memory and an outlook for its future prospects.

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“…Such materials have significant applications because there are large differences in electrical and optical properties between these phases. Up to now, PCMs have been widely used in all-photonic memories [ 1 , 2 , 3 , 4 , 5 , 6 ], color display [ 7 , 8 ], neuro-inspired computing [ 9 ], reconfigurable meta-optics [ 10 , 11 ], photonic switches and routers [ 12 , 13 ], and so on. Among these PCMs, Ge 2 Sb 2 Te 5 (GST) has received considerable attention in terms of its fast phase switching speed, high optical reflectivity, and outstanding scalability [ 1 , 5 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Crystallization Characteristics of Intermediate States in Ge2Sb2Te5 Thin Films Induced by Nanosecond Multi-Pulsed Laser Irradiation

Zhou

Zhang

et al. 2022

Nanomaterials

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Laser pulses can be utilized to induce intermediate states of phase change materials between amorphous and crystalline phases, making phase change materials attractive and applicable for multi-level storage applications. In this paper, intermediate states of Ge2Sb2Te5 thin films induced via employing a nanosecond multi-pulse laser with different energy and pulse duration were performed by Raman spectroscopy, reflection measurement and thermal simulations. Upon laser-crystallized Ge2Sb2Te5 films, optical functions change drastically, leading to distinguishable reflectivity contrasts of intermediate states between amorphous and crystalline phases due to different crystallinity. The changes in optical intensity for laser-crystallized Ge2Sb2Te5 are also accompanied by micro-structure evolution, since high-energy and longer pulses result in higher-level intermediate states (corresponding to high reflection intensity) and largely contribute to the formation of stronger Raman peaks. By employing thermal analysis, we further demonstrated that the variations of both laser fluence and pulse duration play decisive roles in the degree of crystallinity of Ge2Sb2Te5 films. Laser fluence is mainly responsible for the variations in crystallization temperature, while the varying pulse duration has a great impact on the crystallization time. The present study offers a deeper understanding of the crystallization characteristic of phase change material Ge2Sb2Te5.

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Amorphization Optimization of Ge2Sb2Te5 Media for Electrical Probe Memory Applications

Cited by 6 publications

References 23 publications

Design of Phase‐Change Memory Using Apertureless Scanning Near‐Field Optical Microscopy in the Near‐Infrared Region

Design of Phase‐Change Memory Using Apertureless Scanning Near‐Field Optical Microscopy in the Near‐Infrared Region

Overview of Phase-Change Electrical Probe Memory

Investigation of the Crystallization Characteristics of Intermediate States in Ge2Sb2Te5 Thin Films Induced by Nanosecond Multi-Pulsed Laser Irradiation

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